Composite welding method for connector cable

Abstract

The invention discloses a composite welding method for a connector cable. The hybrid welding method comprises the following steps: pretreating a terminal and a conductor, and forming tight contact or an accurate gap between to-be-connected surfaces of the terminal and the conductor; applying pressure to a connection area of the terminal and the conductor by adopting a shaping electrode, and introducing pulse current to locally melt a contact interface of the terminal and the conductor to form initial metallurgical bonding; on an initial bonding area formed by electric resistance welding, a laser beam is adopted to conduct scanning irradiation along the outer side surface of the bonding area, so that the local depth of the bonding area is secondarily fused, and reinforcement and interface optimization of an initial bonding point are achieved; and cooling, cleaning and performance inspection are carried out on the welded connection points. According to the invention, through a composite process of electric resistance welding shaping positioning and laser welding micro-area strengthening, high continuity of geometric and electrical characteristics of a connection interface is realized on the premise of no additional welding flux, so that ultralow high-frequency impedance fluctuation and extremely high mechanical connection strength are obtained at the same time.

Description

Technical Field

[0001] This invention relates to the field of high-speed, high-frequency interconnect technology, and in particular to a composite welding method for connector cables. Background Technology

[0002] With the rapid development of 5G communication, artificial intelligence, high-performance computing, and data center technologies, the demand for data communication speeds and bandwidth is growing exponentially, driving the operating frequencies of high-speed electrical connectors towards millimeter-wave bands (such as 40GHz, 56GHz, and even higher). In such high-frequency applications, any tiny discontinuity in the signal transmission path can cause severe signal reflection, attenuation, and distortion.

[0003] In the manufacturing of high-speed connectors in related technologies, the electrical connection between the connector terminals and the cable conductors (such as the core wires of coaxial or biaxial cables) is achieved by laminating and then soldering (e.g., hotbar soldering). While this process can achieve reliable electrical conduction and mechanical fixation, it exposes inherent and insurmountable defects when dealing with millimeter-wave signal transmission.

[0004] Hotbar soldering requires the introduction of additional tin-based solder. This solder differs from conductors like copper in material and dielectric constant, and its filling shape and volume are difficult to control precisely. This is equivalent to introducing an irregular, high-dielectric-constant heterogeneous material into the transmission path, causing abrupt changes and fluctuations in the characteristic impedance at the connection point. Time-domain reflectometry (TDR) tests show that impedance fluctuations can reach 4 ohms or higher at high frequencies, becoming a bottleneck limiting signal rate increases.

[0005] To achieve welding, conductors are usually overlapped at the ends or on the sides, resulting in physical steps or cross-sections at the connection. This disrupts the smooth transition of the conductors and causes discontinuities in the geometry of the signal transmission path. This not only causes impedance changes but also generates unwanted parasitic capacitance and inductance.

[0006] For low-frequency or DC applications, the above issues may be acceptable. However, in the field of high-frequency connectors, traditional soldering processes, due to their inherent characteristics of introducing heterogeneous materials and causing structural discontinuities, run counter to the core design goals of high bandwidth, low loss, and high signal integrity. Summary of the Invention

[0007] The present invention aims to at least partially solve one of the technical problems in the related art.

[0008] Therefore, embodiments of the present invention propose a composite welding method for connector cables. Through a composite process of resistance welding shaping and positioning and laser welding micro-area strengthening, a high degree of continuity of the geometry and electrical characteristics of the connection interface is achieved without the addition of external solder, thereby simultaneously obtaining ultra-low high-frequency impedance fluctuations and extremely high mechanical connection strength.

[0009] The connector cable composite welding method of this invention includes: The connector terminals and cable conductors are pre-treated and fixed in a preset relative position to make the surfaces to be connected form a tight contact or a precise gap. A pair of shaping electrodes are used to apply pressure to the connection area between the fixed terminal and the conductor, and a pulse current is applied. The Joule heat generated by the contact resistance causes the contact interface between the terminal and the conductor to partially melt and form an initial metallurgical bond, thus completing the mechanical positioning and preliminary electrical connection. In the initial bonding area formed by resistance welding, a laser beam is used to scan and irradiate along the outer surface of the bonding area, causing secondary melting and solidification of the local depth of the bonding area, thereby strengthening the initial bonding point and optimizing the interface. After welding, the joints are cooled, cleaned, and their performance is tested.

[0010] In some embodiments, the shaping electrode includes a resistance welding head and a resistance welding base. The resistance welding base is provided with a T-shaped support platform. The terminal pad is placed on the surface of the support platform near the resistance welding head, the conductor is placed in the center on the surface of the terminal pad, and the resistance welding head is pressed against the conductor to perform resistance welding on the terminal and the conductor.

[0011] In some embodiments, the welding surface of the resistance welding head is provided with a groove to press the conductor into the groove. The groove opening width is consistent with the width of the terminal pad. The width of the groove gradually decreases from the opening to the bottom of the groove to apply lateral extrusion to the conductor and guide its plastic flow and shaping.

[0012] In some embodiments, the resistance welding head and the resistance welding base are made of one of the following materials: tungsten copper alloy, chromium zirconium copper, or dispersion-strengthened copper.

[0013] In some embodiments, during the resistance welding process, a preset pressure is first applied to the resistance welding head to stabilize the contact resistance, then a pulse current of a preset waveform and magnitude is triggered, and the pressure is maintained for a period of time after the current ends. The dynamic resistance value or electrode displacement in the welding circuit is monitored in real time and compared with the preset standard curve. If the deviation exceeds the threshold, the welding is judged as abnormal and marked.

[0014] In some embodiments, after resistance welding is completed, the resistance welding head is removed, and laser welding continues on the support platform under an inert gas protective atmosphere, with the laser spot diameter being less than or equal to the width of the resistance welded joint area.

[0015] In some embodiments, during laser welding, the power of laser welding is dynamically adjusted based on the actual welding energy recorded during resistance welding.

[0016] In some embodiments, the pretreatment of the cable conductor includes: Strip the outer insulation of the cable to expose a predetermined length of conductor; The exposed conductor surface is shaped to form an overlap surface that conforms to the shape of the terminal pad.

[0017] In some embodiments, the performance testing of the welded joint includes: The characteristic impedance of the solder joint is tested using a time-domain reflectometer with a bandwidth of at least 40 GHz. The test standard is that the absolute value of the TDR impedance fluctuation caused by the solder joint is less than or equal to 1 ohm.

[0018] In some embodiments, the performance testing of the welded joints further includes: The axial pull-out force of the welded single wire and terminal connection point is tested by a tensile testing machine. The inspection standard is that the maximum breaking force of the weld point is not less than 6N.

[0019] The connector cable composite welding method of this invention combines the technical advantages of resistance welding and laser welding, resulting in a synergistic and multiplicative technical effect.

[0020] In terms of electrical performance, electrodes with shaping capabilities actively address structural discontinuities and eliminate the introduction of heterogeneous solder. This suppresses characteristic impedance fluctuations caused by solder joints to within 1 ohm at operating frequencies of 40GHz and above, resolving high-frequency signal integrity issues caused by traditional soldering processes and meeting the design requirements of 56GHz and higher speed connectors. In terms of mechanical performance, the high-quality initial metallurgical bond formed by resistance welding, followed by localized reinforcement through laser welding, significantly exceeds conventional standards in pull-out force at the solder joints (reaching over 16N, far exceeding the 6N baseline), resulting in a substantial improvement in connection reliability. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of the connector terminal pads and the initial fixed position of the cable conductor in an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the shaping electrode structure according to an embodiment of the present invention.

[0023] Figure 3This is a schematic diagram of the resistance welding process according to an embodiment of the present invention.

[0024] Figure 4 This is a schematic cross-sectional view of the resistance welding molten deformation according to an embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the structure after resistance welding and deformation according to an embodiment of the present invention.

[0026] Figure 6 This is a schematic diagram of the single-point laser welding structure according to an embodiment of the present invention.

[0027] Figure 7 This is a schematic diagram of the structure of multi-point laser welding according to an embodiment of the present invention.

[0028] Figure 8 This is a side view schematic diagram of the laser welding depth according to an embodiment of the present invention.

[0029] Figure 9 This is a data graph of impedance testing according to an embodiment of the present invention.

[0030] Figure 10 This is a data graph of the tensile test according to an embodiment of the present invention.

[0031] Figure label: 1-Terminal; 2-Conductor; 3-Resistance welding head; 31-Groove; 4-Resistance welding base; 5-Supporting platform; 6-Laser welding point. Detailed Implementation

[0032] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0033] The connector cable composite welding method of the present invention is described below with reference to the accompanying drawings.

[0034] like Figures 1 to 10 As shown, the connector cable composite welding method of this invention includes: The S1 conductor 2 preparation and positioning steps involve pre-processing the connector terminal 1 and the cable conductor 2, and fixing them in a preset relative position so that the surfaces to be connected form a tight contact or a precise gap, thereby constructing the physical basis for high-quality metallurgical connection and excellent electrical performance.

[0035] Pre-treatment ensures the joint surfaces are clean and free of oxide layers and other insulating materials, achieving low contact resistance and good fusion. Precise positioning and fixation of both components establish an initial, geometrically optimal conduction path before welding, minimizing positional shifts during subsequent welding and thus avoiding structural discontinuities and impedance caused by misalignment.

[0036] This step creates stable and repeatable initial conditions for subsequent resistance welding steps, serving as the first guarantee for achieving controllable impedance and highly consistent production. Precise gap or contact control directly affects the uniformity and consistency of heat generation during resistance welding.

[0037] In the S2 resistance welding step, a pair of shaping electrodes are used to apply pressure to the connection area between the fixed terminal 1 and conductor 2, and a pulse current is applied. The Joule heat generated by the contact resistance causes the contact interface between the terminal 1 and conductor 2 to partially melt and form an initial metallurgical bond, thus completing the mechanical positioning and preliminary electrical connection.

[0038] The shaping electrode ensures that pressure is applied evenly to the target area, while its shape design helps conductor 2 to undergo controllable deformation under pressure, optimizing the contact interface. Applying pressure has two key functions: first, to ensure tight contact and stabilize the initial resistance; and second, to provide forging force when the molten metal solidifies, which helps to form a dense weld nugget.

[0039] Applying a pulsed current utilizes the Joule heating effect (Q=I²Rt) to generate concentrated heat at the contact surface between terminal 1 and conductor 2, instantly bringing it to its melting temperature. Under pressure, this allows for atomic diffusion and fusion of the two materials. This process does not involve adding any foreign metal materials, thus avoiding impedance mismatch caused by dissimilar materials at the source.

[0040] Resistance welding forms a preliminary, pure metal-metal metallurgical bond, providing basic mechanical strength and electrical conductivity. The shaping electrode not only transmits pressure and current, but its core function lies in applying lateral constraint and guiding force to the conductor during pressurization through a pressure head with a specific shape (such as a conical groove). This induces controlled plastic flow, actively shaping a smooth transition from the conductor to the solder pad, thereby reducing or eliminating joint breaks.

[0041] In the S3 laser welding step, a laser beam is used to scan and irradiate the outer surface of the initial bonding area formed by resistance welding, causing secondary melting and solidification of the local depth of the bonding area (forming laser weld point 6), thereby strengthening the initial bonding point and optimizing the interface.

[0042] The bonding area formed by resistance welding has microscopically incomplete fusion or uneven microstructure. Laser beams, with their extremely high energy density, concentrated and precisely controllable heat input, can be scanned to achieve: secondary remelting, resulting in a more uniform and dense bonding interface; localized deep melting, increasing the effective bonding area and depth; and surface finishing, optimizing the surface morphology of the bonding area.

[0043] Laser welding's non-contact nature avoids mechanical interference and has a minimal heat-affected zone, preventing damage to surrounding structures and insulation materials. This significantly improves the mechanical reliability (peel force) of the weld joint, enabling the connection to withstand more severe physical stresses. By optimizing the microstructure and geometry of the bonding interface, the electrical signal transmission path is further optimized, ensuring that the excellent impedance continuity established by resistance welding is consolidated and enhanced.

[0044] The S4 post-processing and inspection steps involve cooling, cleaning, and performance testing of the welded joints.

[0045] Controlled cooling reduces welding stress and cleans away spatter and oxides. Inspection ensures that every weld point truly meets design goals for low impedance fluctuations (e.g., <1Ω) and high mechanical strength (e.g., >6N), thus guaranteeing the product's high-frequency electrical performance and high reliability from the production stage.

[0046] The connector cable composite welding method of this invention first utilizes resistance welding under pressure to achieve an additive-free, shape-guided initial metallurgical connection, solving the problems of material purity and initial structural continuity. Subsequently, laser welding is used to perform high-precision, low-heat-affected secondary treatment on the initial connection area, addressing the optimization of interface microstructure and connection strength. The order of these two steps is indispensable; their functions complement each other, together constituting a solution to the challenging problem of high-frequency connector welding.

[0047] By completely eliminating solder and actively eliminating cross-sections using composite processes, a high degree of stability in the characteristic impedance of the connection point is achieved, and TDR fluctuations are suppressed to an extremely low level (such as within 1Ω), meeting the requirements of extreme high-frequency applications at 40GHz and even above 56GHz.

[0048] Resistance welding provides the basic strength, while laser welding provides reinforcement, resulting in overall mechanical properties of the weld joint that far exceed those of traditional processes, with a significant increase in pull-out force. The parameters of both steps can be independently and precisely controlled, making it suitable for automated, large-scale production and ensuring a high degree of consistency in product performance.

[0049] In some embodiments, such as Figures 1 to 5 As shown, the shaping electrode includes a resistance welding head 3 (upper electrode) and a resistance welding base 4 (lower electrode). The resistance welding base 4 is provided with a T-shaped support platform 5. The terminal 1 pad is placed on the surface of the support platform 5 near the resistance welding head 3, the conductor 2 is placed in the center on the surface of the terminal 1 pad, and the resistance welding head 3 is pressed against the conductor 2 to perform resistance welding on the terminal 1 and the conductor 2.

[0050] The horizontal platform of the support table 5 is used to support and carry the connector terminal 1, providing a stable, highly flat reference surface for the terminal 1 and preventing bending or displacement of the terminal 1 during welding. Furthermore, the T-shaped support table 5 is suitable for welding biaxial cables, and the underside of the support table 5 has space to allow it to pass through the two conductors 2 of the biaxial cable (e.g., ...). Figure 3 and Figure 7 (As shown). First, weld the conductor 2 on the upper surface of the support platform 5. After the conductor 2 is welded, flip the lower conductor 2 onto the upper surface of the support platform 5 for welding.

[0051] The pads to be welded (i.e., the specific welding area on terminal 1) are placed upwards, directly exposed and facing the resistance welding head 3 that is about to press down, ensuring that the welding energy can be applied directly and accurately to the target area. At the same time, the rest of terminal 1 (such as the plastic body and the plug part) is avoided by the support platform 5, preventing unnecessary stress or damage.

[0052] Centering conductor 2 ensures symmetrical welding and uniform impedance distribution after welding. Guided by the operator's vision, simple fixtures, or automated equipment, the cable conductor 2 (such as the stripped core wire) is placed on the center line of the width of the terminal 1 pad. This allows the conductor 2 to deform symmetrically to both sides during subsequent crimping, forming the optimal contact area with the terminal 1 pad, thereby achieving uniform current distribution and weld nugget growth.

[0053] The resistance welding head 3 serves as the upper electrode, and its lower surface has a specific shape. When the resistance welding head 3 moves downward and presses against the conductor 2, the shape of the head first further positions the conductor 2, which may be slightly warped or offset, towards the center of the pad. The pressure causes plastic deformation of the micro-protrusions on the surface of the conductor 2 and the pad of the terminal 1, and the actual contact area increases rapidly, thereby forming a stable and predictable initial contact resistance.

[0054] During the energizing phase, the current flows through the path of pressure head - conductor 2 - terminal 1 - base. Simultaneously, the continuous pressure prevents the contact surfaces from separating due to expansion during heating, thus preventing the formation of an electric arc. Furthermore, the forging force applied during metal moltenness helps to expel any potential pores and shrinkage cavities, resulting in a dense weld nugget.

[0055] Optionally, such as Figure 1 and Figure 4 As shown, the welding surface of the resistance welding head 3 is provided with a groove 31 so that the conductor 2 is pressed into the groove 31. The width of the groove 31 is consistent with the width of the terminal 1 welding pad.

[0056] The groove width is consistent with the pad width. That is, when the resistance welding head 3 is pressed down, the side wall of the groove 31 can accurately span over or align with the two sides of the pad of terminal 1, ensuring that the conductor 2 is confined within the pad width range during the pressurization process, preventing it from sliding laterally or overflowing.

[0057] The correspondence between the sidewall of the groove 31 and the edge of the pad essentially helps to define the main lateral diffusion range of the current from the pressure head to the terminal 1 when energized, so that the current flows more concentratedly through the interface area to be welded, improving energy utilization efficiency and heating uniformity.

[0058] Furthermore, the width of the groove 31 gradually decreases along the direction from the groove opening to the bottom of the groove, that is, the longitudinal section of the groove 31 is an inverted trapezoidal or conical structure.

[0059] When the resistance welding head 3 presses against the circular or near-circular cable conductor 2, this structure generates active metal flow control. The gradually narrowing sidewalls apply an inward horizontal force to the conductor 2. Under the combined effect of pressure and current heating, the conductor 2 undergoes plastic deformation, and the material is not only vertically compacted but also guided by the conical space to flow and fill to the sides and downwards (pad interface).

[0060] Controlled flow energy effectively fills the microscopic gaps between conductor 2 and the surface of the terminal 1 pad, as well as between conductor 2 itself and the sidewall of groove 31, maximizing the actual contact area, reducing contact resistance, and making the generation of Joule heat more uniform. Furthermore, the final deformation shape of conductor 2 is no longer a simple circular flattening, but rather an approximate trapezoidal or rectangular shape formed under the constraint of groove 31, with a slightly concave upper surface, a good lower surface fits well with the pad, and a smooth side transition, thus optimizing the cross-sectional shape of the welding area.

[0061] Optionally, the resistance welding head 3 and the resistance welding base 4 are made of one of the following materials: tungsten copper alloy, chromium zirconium copper, or dispersion-strengthened copper.

[0062] Electrodes are carriers of large currents (thousands to tens of thousands of amperes), and their own resistance must be extremely low to concentrate electrical energy onto the contact interface between the workpiece (terminal 1 and conductor 2) to the greatest extent possible, rather than wasting it on the electrode's own heating. Copper is a substrate with excellent conductivity. All three materials have other elements added to the copper matrix, but through specific processes, their overall conductivity is still maintained at a high level, ensuring that welding energy is efficiently and controllably transferred to the welding area, which is a prerequisite for achieving stable and consistent welding heat input.

[0063] Tungsten-copper alloy (W-Cu) utilizes a high-hardness, high-melting-point tungsten skeleton (formed through powder metallurgy sintering) to withstand mechanical pressure and resist deformation, while a copper phase fills the skeleton and ensures electrical and thermal conductivity.

[0064] Chromium-zirconium copper (CuCrZr) forms fine intermetallic compound particles of chromium and zirconium in a copper matrix through solid solution treatment and aging precipitation. These particles can effectively hinder dislocation movement, thereby significantly improving the strength and hardness of the material (i.e. precipitation strengthening).

[0065] Dispersion-strengthened copper is produced by uniformly distributing extremely fine and stable oxide particles within a copper matrix through processes such as internal oxidation. These particles do not dissolve or coarsen at high temperatures and strongly pin dislocations and grain boundaries, providing stable strengthening effects from room temperature to high temperatures.

[0066] When the electrode is subjected to repeated, high-frequency impact pressure (several kilograms to tens of kilograms), its working surface (especially the groove 31 structure) can resist plastic deformation and crushing, and maintain its initial geometric shape and dimensional accuracy for a long time.

[0067] During resistance welding, the electrode tip repeatedly contacts the high-temperature workpiece (locally reaching above the melting point of copper), and its own temperature also rises (up to several hundred degrees Celsius). Ordinary copper or copper alloys will soften rapidly and their strength will drop sharply at this temperature.

[0068] The tungsten skeleton of tungsten-copper alloys has extremely high melting points and recrystallization temperatures, exhibiting almost no softening at welding temperatures and demonstrating structural stability. The reinforcing phases (precipitates or oxide particles) of chromium-zirconium copper and dispersion-strengthened copper possess high thermal stability at high temperatures, are not easily dissolved or coarsened, and therefore maintain their strength and hardness over long periods at high operating temperatures. This ensures that the hardness and strength of the electrode's working end do not significantly decrease during continuous operation or after thermal shock, thereby maintaining consistent welding pressure, stable contact resistance, and preventing the electrode tip from sticking to the workpiece due to high-temperature deformation.

[0069] The precise geometry of the electrode groove 31 is key to achieving optimized interface and reduced cross-section. The high strength, high hardness, and high-temperature softening resistance of the selected material ensure that this precise shape will not wear, deform, or collapse during thousands of welding cycles, thus providing a long-term, stable output of its shaping function and guaranteeing the hardware durability foundation for each weld point to achieve the expected excellent electrical performance (low TDR fluctuation).

[0070] In some embodiments, during the resistance welding process, the resistance welding head 3 is first subjected to a preset pressure to stabilize the contact resistance, then a pulse current of a preset waveform and magnitude is triggered, and the pressure is maintained for a period of time after the current ends.

[0071] Contact resistance is the only source of welding heat, but its initial value is extremely unstable and affected by random factors such as surface oxidation, flatness, and pressure. If current is applied when the contact is unstable, it can lead to localized instantaneous overheating (arcing), ablation, or uneven heat distribution.

[0072] Before power is applied, a preset, constant pre-pressure is applied. This pressure causes plastic deformation of the micro-bumps on the surface of the pads of conductor 2 and terminal 1, rapidly increasing and stabilizing the actual contact area, thereby turning the highly variable initial contact resistance into a stable, predictable low value.

[0073] Based on stable contact, a precisely controlled pulsed current is applied. Preset current waveforms (such as rise time, peak value, duration, and fall time) and magnitudes are designed to input just enough energy into the interface to bring the local metal to its melting temperature without causing splashing or overheating. Precise current control based on stable contact resistance enables the generation of melt nuclei with controllable position, size, and shape.

[0074] After the current is dissipated, the molten metal nucleus begins to solidify. During solidification, the metal shrinks and may produce defects such as shrinkage cavities and cracks. Maintaining (or even finely adjusting) the pressure for a period of time can effectively compensate for the metal's solidification shrinkage, promote the densification of the internal structure of the weld nucleus, squeeze out any possible impurities or gases, and help refine the grains, thereby significantly improving the mechanical strength and conductivity of the weld nucleus.

[0075] Furthermore, the dynamic resistance value or electrode displacement in the welding circuit is monitored in real time and compared with the preset standard curve. If the deviation exceeds the threshold, the welding is judged to be abnormal and marked.

[0076] During welding, the resistance at the contact interface changes dramatically. As the metal is heated, softened, melted, and solidified, the dynamic resistance curve exhibits a specific fingerprint-like pattern: a rapid initial drop (increased contact area), followed by a rise (thermal expansion of the metal and reduction of contact points), and finally stabilization or a further drop (melting to form a liquid phase bridge). Electrode displacement also reflects the degree of thermal expansion and melting of the metal.

[0077] The standard curve is an ideal template for a good weld, derived from a large number of qualified process tests, representing the dynamic resistance-time curve or displacement-time curve.

[0078] The real-time signal curve for each weld is compared with a standard curve. If the key characteristics such as the shape, peak value, and inflection point time are within the allowable threshold range, the weld process is considered normal. If significant deviations occur (for example, a slow resistance drop may indicate insufficient pressure, and an early resistance peak may indicate excessive current or poor contact), it is considered abnormal.

[0079] This enables a shift from traditional post-weld inspection to a real-time prediction and proactive quality control model, allowing potential defects to be identified the moment welding is completed, or even during the welding process.

[0080] In some embodiments, such as Figures 6 to 8As shown, after resistance welding is completed, the resistance welding head 3 is removed, and laser welding continues on the support platform 5 under an inert gas protective atmosphere.

[0081] The resistance welding head 3 has been removed, and the workpiece (the assembly of terminal 1 and conductor 2, which has undergone preliminary welding) remains on the support platform 5. An inert gas protective atmosphere has been established above the welding area. The laser's optical system (such as the galvanometer and focusing lens) is in place. The focus of the laser beam has been calibrated onto the initial bonding area formed by the resistance welding step.

[0082] The laser beam is guided to the upper surface of the initial bonding area. The laser beam is controlled to move quickly and precisely along a preset path (such as single-point or multi-point scanning along the extension direction of the bonding area). The laser spot diameter is less than or equal to the width of the resistance welding bonding area, ensuring that the laser energy can be highly concentrated on the interface area that needs to be reinforced without overheating the surrounding base material or insulation layer.

[0083] A high-energy-density laser beam is instantly irradiated onto a metal surface, where energy is rapidly absorbed, causing the metal surface layer (and even a certain depth) at the irradiation point to reach a molten state in a very short time. Since the resistance welding has already completed the initial bonding, the metal continuity at this point is good. The laser's melting and solidification process can further homogenize and densify the microstructure (such as grains and eutectic phases) of the bonding interface region.

[0084] Furthermore, during the laser welding process, the laser welding power is dynamically adjusted based on the actual welding energy recorded during the resistance welding process.

[0085] Actual welding energy (usually the integral of current over time, or the total Joule heat calculated from voltage and current) is a comprehensive quantitative indicator of the heat input in resistance welding. This measured energy value is compared with a nominal energy (or an ideal energy range).

[0086] If the measured energy is higher than expected, it is inferred that the resistance welding heat is sufficient, and the weld nugget may be larger or the heat-affected zone wider. To prevent overheating caused by laser superposition, it is decided to appropriately reduce the power of subsequent lasers to reduce the total heat input.

[0087] If the measured energy is lower than expected, it is inferred that the initial melt nucleus may be insufficient. The decision is to increase the laser power to achieve compensatory reinforcement through stronger secondary melting and solidification, ensuring that the final strength meets the requirements.

[0088] In some embodiments, the pretreatment of the cable conductor 2 includes: Strip the outer insulation of the cable to expose the conductor 2 of a predetermined length, creating a clean, accessible metal interface. The outer insulation is necessary for physical insulation, but it must be precisely removed during soldering to expose the internal metal conductor 2 (usually copper or plated copper).

[0089] The length of the exposed conductor 2 directly determines the effective soldering area and the length of the unshielded section in the signal transmission path. If it is too short, the effective contact area will be insufficient, affecting the connection resistance and strength; if it is too long, an unshielded antenna or transmission line discontinuity will be generated near the soldering point, which may cause unnecessary electromagnetic radiation, signal leakage, or impedance disturbances at extremely high frequencies.

[0090] A uniform exposure length is a geometric benchmark that ensures the consistency of all subsequent welding parameters (such as electrode crimping position and laser scanning path), ensuring that the initial conditions of the working end of each cable are the same when it enters the welding station.

[0091] The exposed surface of conductor 2 is shaped to form an overlap surface that matches the shape of the terminal 1 pad.

[0092] The conductor 2 of a standard cable (especially stranded or small-diameter solid wire) typically has a circular cross-section. The connector terminal 1 pad, however, is usually a flat surface or a surface with a slight curvature. The initial contact between the circle and the surface is a point or line contact, with a small and unstable actual contact area. The exposed conductor 2 end can be plastically deformed using mechanical means (such as precision die flattening, rolling, or cutting) to change its cross-sectional shape from circular to a shape that better matches the pad surface, such as a flat rectangular surface or an arc surface with a specific curvature.

[0093] After shaping, the width and curvature of the lap surface of conductor 2 match the surface contour of the pad of terminal 1, enabling a large-area initial surface contact to be formed when the two are bonded together, rather than multi-point contact. The shaping process (such as fresh plastic deformation) can also break the oxide layer and contamination layer on the surface of conductor 2, exposing fresh, clean, and highly active metal lattice, reducing contact resistance and promoting subsequent metallurgical bonding.

[0094] In some embodiments, the performance testing of the welded joint includes: The characteristic impedance of the solder joint is tested using a time-domain reflectometer with a bandwidth of at least 40 GHz. The test standard is that the absolute value of the TDR impedance fluctuation caused by the solder joint is less than or equal to 1 ohm.

[0095] like Figure 9 As shown, the TDR curves are the test results at 40GHz. The red curve represents traditional soldering with an impedance fluctuation of about 4 ohms, while the blue curve represents soldering according to the embodiment of the present invention with an impedance fluctuation of less than 1 ohm.

[0096] In this embodiment of the invention, no additional metal solder is introduced at the conductor connection, thus avoiding TDR impedance fluctuations. When the operating bandwidth of high-speed connectors reaches up to 40GHz, traditional hotbar soldering introduces a TDR fluctuation of about 4 ohms, while the composite welding of resistance soldering and laser soldering in this embodiment of the invention has an impedance fluctuation of less than 1 ohm. This method can support the design and production needs of high-speed connectors at higher frequencies (e.g., 56GHz).

[0097] In some embodiments, the performance testing of the welded joints further includes: The axial pull-out force of the welded single wire and terminal connection point is tested by a tensile testing machine. The inspection standard is that the maximum breaking force of the weld point is not less than 6N.

[0098] like Figure 10 As shown, tensile test data after welding (>6N after laser) is provided.

[0099] The table below summarizes the samples and tensile forces after using the welding method of this invention.

[0100]

[0101] The measured tensile forces of the seven samples (numbered 1499-1505) were 16.2 N, 16.47 N, 15.92 N, 16.64 N, 16.52 N, 17.98 N, and 16.06 N, respectively. All measured values ​​were significantly higher than the minimum standard of 6 N, with the lowest value being 15.92 N. Except for one sample with a value of 17.98 N, the data for the remaining samples were concentrated in a narrow range of 16.0 N to 16.6 N (with a range of approximately 0.7 N), demonstrating the consistency of the process and the predictability of the results.

[0102] A maximum tensile strength of not less than 6N is a verified minimum strength level with sufficient safety margin, ensuring that every welded joint that passes inspection has sufficient strength to withstand mechanical loads such as insertion and extraction forces, cable stress, and vibration that may be encountered during installation and use.

[0103] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0104] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0105] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0106] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0107] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0108] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for composite welding of connector cables, characterized in that, include: The connector terminals and cable conductors are pre-treated and fixed in a preset relative position to make the surfaces to be connected form a tight contact or a precise gap. A pair of shaping electrodes are used to apply pressure to the connection area between the fixed terminal and the conductor, and a pulse current is applied. The Joule heat generated by the contact resistance causes the contact interface between the terminal and the conductor to partially melt and form an initial metallurgical bond, thus completing the mechanical positioning and preliminary electrical connection. In the initial bonding area formed by resistance welding, a laser beam is used to scan and irradiate along the outer surface of the bonding area, causing secondary melting and solidification of the local depth of the bonding area, thereby strengthening the initial bonding point and optimizing the interface. After welding, the joints are cooled, cleaned, and their performance is tested.

2. The connector cable composite welding method according to claim 1, characterized in that, The shaping electrode includes a resistance welding head and a resistance welding base. The resistance welding base is provided with a T-shaped support platform. The terminal pad is placed on the surface of the support platform near the resistance welding head, the conductor is placed in the center on the surface of the terminal pad, and the resistance welding head is pressed against the conductor to perform resistance welding on the terminal and the conductor.

3. The connector cable composite welding method according to claim 2, characterized in that, The welding surface of the resistance welding head is provided with a groove to press the conductor tightly in the groove. The width of the groove opening is consistent with the width of the terminal pad. The width of the groove gradually decreases from the opening to the bottom of the groove to apply lateral extrusion to the conductor and guide its plastic flow and shaping.

4. The connector cable composite welding method according to claim 2, characterized in that, The resistance welding head and resistance welding base are made of one of the following materials: tungsten copper alloy, chromium zirconium copper, or dispersion-strengthened copper.

5. The connector cable composite welding method according to claim 2, characterized in that, During resistance welding, a preset pressure is first applied to the resistance welding head to stabilize the contact resistance, then a pulse current with a preset waveform and magnitude is triggered, and the pressure is maintained for a period of time after the current ends. The dynamic resistance value or electrode displacement in the welding circuit is monitored in real time and compared with the preset standard curve. If the deviation exceeds the threshold, the welding is judged as abnormal and marked.

6. The connector cable composite welding method according to claim 2, characterized in that, After resistance welding is completed, the resistance welding head is removed, and laser welding continues on the support platform under an inert gas protective atmosphere. The diameter of the laser spot is less than or equal to the width of the resistance welded joint area.

7. The connector cable composite welding method according to claim 6, characterized in that, During laser welding, the power of laser welding is dynamically adjusted based on the actual welding energy recorded during resistance welding.

8. The connector cable composite welding method according to claim 1, characterized in that, The pretreatment of cable conductors includes: Strip the outer insulation of the cable to expose a predetermined length of conductor; The exposed conductor surface is shaped to form an overlap surface that conforms to the shape of the terminal pad.

9. The connector cable composite welding method according to claim 1, characterized in that, The performance inspection of the joints after welding includes: The characteristic impedance of the solder joint is tested using a time-domain reflectometer with a bandwidth of at least 40 GHz. The test standard is that the absolute value of the TDR impedance fluctuation caused by the solder joint is less than or equal to 1 ohm.

10. The connector cable composite welding method according to claim 9, characterized in that, The performance inspection of the joints after welding also includes: The axial pull-out force of the welded single wire and terminal connection point is tested by a tensile testing machine. The inspection standard is that the maximum breaking force of the weld point is not less than 6N.

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