Manufacturing process of high-weldability special-shaped contact strip

Abstract

The invention discloses a high-weldability special-shaped contact strip manufacturing process, and particularly relates to the technical field of metal material processing, the high-weldability special-shaped contact strip manufacturing process comprises the following steps: S1, respectively pretreating composite surfaces of a Cu strip and an AgCuP alloy strip or an AgCuZn alloy strip; s2, the pretreated Cu strip and an AgCuP or AgCuZn alloy strip are overlapped, hot rolling compounding is carried out under the conditions that the temperature ranges from 480 DEG C to 520 DEG C and the pressure ranges from 800 MPa to 900 MPa, and the total rolling reduction ranges from 35% to 45%; and S3, on-line annealing is immediately carried out after hot rolling compounding, and treatment is carried out for 60-90 seconds at the temperature of 650 + / -10 DEG C in the protective atmosphere. The AgCuP or AgCuZn alloy is adopted as the welding layer, by means of the low-melting-point characteristic and good wettability of the AgCuP or AgCuZn alloy, the difficulty of the welding technology is greatly reduced, firm metallurgical bonding can be formed with the welding flux without high temperature, common defects such as pseudo soldering and desoldering are effectively reduced, the design of the surface arc-shaped protrusion structure is matched, the welding flux infiltration path is further optimized, and the welding quality is improved. And the welding interface bonding is more uniform and compact, and the reliability of the product in long-term service is fundamentally improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal material processing, and in particular to a manufacturing process of a high-weldability special-shaped contact strip. Background Art

[0002] With the rapid development of the electronic information industry, various electronic devices are evolving towards miniaturization, integration, and high performance, placing increasingly stringent demands on the soldering performance of contact strips. In the field of contact strip manufacturing, traditional processes typically use CuNi9Sn2 composite material on a Cu substrate as the base soldering material. Due to its maturity and cost-effectiveness, this process has long been the mainstream. However, with the widespread adoption of emerging technologies such as 5G communications, artificial intelligence, and the Internet of Things, the soldering environment within electronic devices has become increasingly complex, and the demand for soldering reliability has reached unprecedented levels.

[0003] Against this backdrop, the traditional CuNi9Sn2 / Cu composite process has gradually revealed its many limitations. From a welding operation perspective, the CuNi9Sn2 material exhibits a high process sensitivity during welding. Even small fluctuations in welding parameters can significantly affect welding quality, greatly increasing the difficulty of welding operations. In actual production, problems such as cold solder joints and desoldering are frequent, especially in welding operations on precision electronic equipment such as high-end servers and smartphone chip modules. According to statistics, when contact strips produced using traditional processes are used in such equipment, the welding defect rate is as high as 5%-8%, seriously restricting the product yield and production efficiency.

[0004] A deeper dive into the reasons for this failure reveals that the unique chemical composition and physical properties of CuNi9Sn2 lie primarily in its metallurgical reactivity with other metals during high-temperature welding, making it difficult to form stable, high-strength intermetallic compounds. This results in insufficient bond strength at the weld interface. Furthermore, its coefficient of thermal expansion differs significantly from that of common electronic component materials. Temperature fluctuations can easily generate thermal stress in the weld area, further reducing the reliability of the weld connection and severely impacting the product's lifespan and overall performance. Summary of the Invention

[0005] The object of the present invention is to provide a process for manufacturing a highly weldable special-shaped contact strip to address the above-mentioned deficiencies in the technology.

[0006] To achieve the above-mentioned object, the present invention provides the following technical solution: A process for manufacturing a highly weldable special-shaped contact strip, comprising: S1, pretreating the composite surfaces of a Cu strip and an AgCuP alloy strip or an AgCuZn alloy strip;

[0007] S2. Laminating the pretreated Cu strip with the AgCuP or AgCuZn alloy strip, and hot rolling the strip at a temperature of 480-520° C. and a pressure of 800-900 MPa, with a total reduction of 35%-45%;

[0008] S3. Immediately after hot rolling and lamination, perform online annealing: treat at 650±10℃ for 60-90 seconds in a protective atmosphere;

[0009] S4, subjecting the annealed composite strip to a wire drawing and reducing process, and then precision rolling using a special-shaped roller die to form a special-shaped strip having a raised contact structure;

[0010] S5. Compounding an AgNi10 alloy layer on the surface of the raised contact.

[0011] Preferably, the pretreatment in step S1 comprises sandblasting roughening treatment and ultrasonic cleaning of the composite surface, and the roughness Ra of the composite surface after treatment is 1.0 to 1.5 μm.

[0012] Preferably, the online annealing in step S3 is carried out in a continuous annealing furnace, the strip traveling speed is 5 to 8 m / min, and the protective atmosphere is argon with an oxygen content of ≤50 ppm.

[0013] Preferably, the special-shaped rolling in step S4 includes two stages:

[0014] The first stage: rolling the composite strip into a flat strip;

[0015] The second stage: an arc-shaped raised structure is rolled out on the edge of the strip through a special-shaped roller die, with a raised height of 0.1 to 0.15 mm.

[0016] Preferably, in step S5, an AgNi 10 alloy layer is formed by electroplating or magnetron sputtering, with a thickness of 2 to 5 μm.

[0017] A highly weldable special-shaped contact strip, produced by the above process, comprises a three-layer composite structure and functional characteristics:

[0018] Top contact layer: AgNi10 alloy layer provided on the top surface of the strip, serving as the electrical contact functional interface;

[0019] Intermediate substrate layer: The Cu layer located below the AgNi10 layer, which performs the core conductive and mechanical support functions;

[0020] Bottom soldering layer: AgCuP or AgCuZn alloy layer compounded on the bottom surface of Cu layer, the bottom surface of which is processed with arc-shaped convex structure with a height of 0.1 to 0.15 mm, and the convexity is in direct contact with the solder.

[0021] In the above technical solution, the technical effects and advantages provided by the present invention are:

[0022] 1. Using AgCuP or AgCuZn alloy as the welding layer, with its low melting point and good wettability, greatly reduces the difficulty of the welding process. It can form a strong metallurgical bond with the solder without high temperature, effectively reducing common defects such as cold solder joints and desoldering. Combined with the surface arc-shaped convex structure design, it further optimizes the solder infiltration path, making the welding interface more uniform and dense, fundamentally improving the reliability of the product in long-term service.

[0023] 2. The synergistic process of hot-rolling pre-combination and online annealing promotes the formation of a high-strength metallurgical bond at the material interface: the high pressure and high temperature during hot rolling promote full atomic diffusion, while online annealing eliminates internal stress and strengthens the interfacial bonding force, ensuring that the various layers of the strip remain tightly fitted during long-term use, eliminating performance degradation caused by delamination and meeting the stringent requirements of high-reliability scenarios.

[0024] 3. Using Cu as the intermediate substrate layer and taking advantage of its excellent heat dissipation performance, while ensuring the electrical conductivity and mechanical support functions, it can significantly reduce the component's dependence on external heat dissipation structures and simplify the packaging design; the cost of Cu material itself is lower than that of precious metals. Combined with the gradient structure design of the thin layer of precious metal plating, it can effectively control material costs while achieving high performance, taking into account both technological advancement and economic rationality. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0026] Figure 1 This is a schematic diagram of the structure of the original AgNi10 / CuNi9Sn2 combination in the present invention;

[0027] Figure 2 Schematic diagram of the structure of AgNi10 / Cu / AgCuP combination in the present invention;

[0028] Figure 3 It is a schematic diagram of the actual metallographic structure of the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0030] The present invention provides Figures 1 to 3A manufacturing process for a high-weldability special-shaped contact strip is shown, comprising: S1, pre-treating the composite surfaces of the Cu strip and the AgCuP alloy strip or the AgCuZn alloy strip;

[0031] S2. Laminating the pretreated Cu strip with the AgCuP or AgCuZn alloy strip, and hot rolling the strip at a temperature of 480-520° C. and a pressure of 800-900 MPa, with a total reduction of 35%-45%;

[0032] S3. Immediately after hot rolling and lamination, perform online annealing: treat at 650±10℃ for 60-90 seconds in a protective atmosphere;

[0033] S4, subjecting the annealed composite strip to a wire drawing and reducing process, and then precision rolling using a special-shaped roller die to form a special-shaped strip having a raised contact structure;

[0034] S5. Compounding an AgNi10 alloy layer on the surface of the raised contact.

[0035] The pretreatment in step S1 includes sandblasting roughening and ultrasonic cleaning of the composite surface. After the treatment, the roughness Ra of the composite surface is 1.0-1.5 μm.

[0036] The online annealing in step S3 is carried out in a continuous annealing furnace, the strip travel speed is 5 to 8 m / min, and the protective atmosphere is argon with an oxygen content of ≤50 ppm.

[0037] The special-shaped rolling in step S4 includes two stages:

[0038] The first stage: rolling the composite strip into a flat strip;

[0039] The second stage: an arc-shaped raised structure is rolled out on the edge of the strip through a special-shaped roller die, with a raised height of 0.1 to 0.15 mm.

[0040] In step S5, an AgNi10 alloy layer is formed by electroplating or magnetron sputtering, with a thickness of 2 to 5 μm.

[0041] A highly weldable special-shaped contact strip, comprising a three-layer composite structure and functional features:

[0042] Top contact layer: AgNi10 alloy layer provided on the top surface of the strip, serving as the electrical contact functional interface;

[0043] Intermediate substrate layer: The Cu layer located below the AgNi10 layer, which performs the core conductive and mechanical support functions;

[0044] Bottom soldering layer: AgCuP or AgCuZn alloy layer compounded on the bottom surface of Cu layer, the bottom surface of which is processed with arc-shaped convex structure with a height of 0.1 to 0.15 mm, and the convexity is in direct contact with the solder.

[0045] Example 1

[0046] Process flow:

[0047] (1) Pretreatment process (S1)

[0048] Sandblasting: The composite surface of the Cu strip and AgCuP / AgCuZn alloy strip is sandblasted using 80-120 mesh abrasive to achieve a surface roughness of Ra = 1.0-1.5μm. Principle: The roughened surface increases the interfacial contact area through mechanical engagement and simultaneously removes the surface oxide film, providing a clean metallurgical bonding base for subsequent hot rolling and lamination.

[0049] Ultrasonic cleaning: Clean at 40kHz for 5 minutes to remove sandblasting particles and oil residue. This is like washing dishes with a coarse sponge to remove stubborn stains, followed by rinsing with clean water to ensure the interface is free of impurities that could interfere with bond strength.

[0050] (2) Hot rolling composite process (S2)

[0051] Parameter control: temperature 480-520°C, pressure 800-900 MPa, total reduction 35%-45%. Taking Example 1 as an example, a 0.8 mm thick strip is reduced to 0.48 mm after a 40% reduction.

[0052] Key Technical Points: High temperature softens the metal lattice, while high pressure promotes atomic diffusion to form a metallurgical bond. Extension: Insufficient reduction (<35%) will result in insufficient interface bonding, while exceeding 45% may cause cracks due to excessive deformation.

[0053] (3) Online annealing process (S3)

[0054] Continuous annealing furnace: The strip travel speed is 5 to 8 m / min and is kept at 650±10°C in an argon atmosphere (oxygen content ≤ 50 ppm) for 60 to 90 seconds.

[0055] Key Roles:

[0056] Eliminate hot rolling residual stress and prevent embrittlement during subsequent processing;

[0057] It promotes further diffusion of interface atoms and improves the bonding strength (the bonding strength in Example 1 reaches 280 MPa).

[0058] 4) Special-shaped rolling process (S4)

[0059] Two-stage rolling:

[0060] Flat strip rolling: The composite strip is rolled into a flat shape with a specific width (e.g. 6 mm) and thickness (e.g. 0.3 mm) to provide a uniform base for subsequent raised structures;

[0061] Arc-shaped convex forming: A convex with a height of 0.1 to 0.15 mm (e.g., an arc radius of R0.3 mm) is rolled out on the edge of the strip using a special-shaped roller die. Function: The convex structure can increase the solder contact area and improve welding reliability.

[0062] (5) Surface composite process (S5)

[0063] Preparation of AgNi10 alloy layer: electroplating (current density 3A / dm 2 ) or magnetron sputtering to form a 2 to 5 μm thick coating.

[0064] Functional advantages:

[0065] AgNi10 alloy combines high conductivity (Ag-based) with arc erosion resistance (Ni particle reinforcement), and can extend the service life as an electrical contact interface.

[0066] Performance test results:

[0067] Welding tension: ≥120N (copper-steel welding);

[0068] Bonding strength: ≥280MPa (shear test);

[0069] Protrusion structure retention rate: 100% (after 1000 times of mechanical friction).

[0070] Example 2

[0071] Differentiation parameters:

[0072] Online annealing: the protective atmosphere was changed to nitrogen (oxygen content 80 ppm), and the other conditions were the same as in Example 1.

[0073] Results comparison:

[0074] The welding tensile force dropped to 95N and the bonding strength dropped to 230MPa (oxidation caused interface weakening).

[0075] Comparative Example 1 (Verification of the Necessity of Pretreatment)

[0076] Process adjustment:

[0077] S1 omitted sandblasting and only ultrasonic cleaning was performed, and the composite surface roughness Ra = 0.5 μm.

[0078] result:

[0079] After hot rolling, delamination occurs at the interface (XRD shows thickening of the oxide at the interface between Cu and AgCuP), and the steel cannot pass subsequent rolling.

[0080] Comparative Example 2 (Verification of Annealing Timeliness)

[0081] Process adjustment:

[0082] S3 annealing was delayed to 2 hours after hot rolling (cooling at room temperature), and the other conditions were the same as in Example 1.

[0083] result:

[0084] When the welding tensile force was reduced to 80N, the raised structure collapsed during the friction test (residual stress caused embrittlement).

[0085] Comparative Example 3 (Verification of the special-shaped rolling stage)

[0086] Process adjustment:

[0087] S4 only performs flat strip rolling and omits the arc-shaped convex structure.

[0088] result:

[0089] The contact resistance of the contacts increases to 25mΩ (the raised structure optimizes the contact area), and the welding reliability decreases by 30%.

[0090] Comparative Example 4 (Verification of the Necessity of AgNi10 Layer)

[0091] Process adjustment:

[0092] S5 omits the AgNi10 layer and directly uses the AgCuP surface.

[0093] result:

[0094] The welding tension is reduced to 70N (the oxide layer hinders melting), and the resistivity increases by 50% at high temperature (200℃).

[0095]

[0096] Test Method

[0097] Reference Standards

[0098] Welding tensile force: IEC60207 Article 5.3 (copper-steel welding tensile force ≥ 100N).

[0099] Contact resistance: ASTM B571 (test current 1A, ambient temperature 25±2℃).

[0100] Salt spray test: ASTM B117 (5% NaCl solution, 48 hours).

[0101] Supplementary test conditions

[0102] High temperature resistivity: 200℃ for 24 hours, record data every hour.

[0103] Friction test: ISO1639 (100,000 cycles, load 5N, sliding speed 0.5m / s)

[0104] Summary of technical effects

[0105] Interface bonding strengthening: Sandblasting + argon annealing increases the Cu / AgCuP interface bonding strength by 40%.

[0106] Function of raised structure: The arc design reduces contact resistance by 30% and extends service life by 2 times.

[0107] AgNi10 layer advantages: oxidation resistance increased by 5 times, and welding reliability reached 1.8 times the industry standard (IEC60207).

[0108] 1. Significantly improved interface bonding strength

[0109] The key role of pretreatment process

[0110] A combined sandblasting roughening (Ra = 1.0-1.5 μm) and ultrasonic cleaning treatment removed the surface oxide film and formed a micromechanical interlocking structure. Comparing Example 1 with Comparative Example 1: When sandblasting was omitted, the interface delamination occurred due to the thickening of the oxide layer (XRD verification). However, the standard process achieved a Cu / AgCuP interface shear strength of 280 MPa, a 40% improvement over the conventional process without pretreatment.

[0111] Principle: The specific surface area of the rough surface (such as 80-120 mesh sandblasting) increases by 2.5 times, providing more nucleation sites for atomic diffusion, similar to the "jigsaw puzzle bite" effect to strengthen metallurgical bonding.

[0112] Aging Strengthening by Online Annealing

[0113] Annealing immediately after hot rolling at 650°C in argon (oxygen content ≤ 50 ppm) eliminates over 90% of residual stress and promotes atomic interdiffusion between Cu and AgCuP at the interface (the diffusion coefficient increases by 3 times). Compared to Example 2 (nitrogen protection, oxygen content 80 ppm), the weld tension is reduced from 120N to 95N, demonstrating the key role of a low-oxygen atmosphere in inhibiting oxidation and maintaining bond strength.

[0114] 2. Welding reliability breaks through industry standards

[0115] Welding tension and interface stability

[0116] Under standard processes, the copper-steel weld force is ≥120N, exceeding the IEC60207 standard (≥100N) by 20%. In Comparative Example 4, after omitting the AgNi10 layer, the weld force drops to 70N due to oxidation of the AgCuP surface, forming a high-resistance layer that hinders solder melt wetting (the contact angle increases from 30° to 65°).

[0117] The synergistic mechanism of the bump structure: 0.1-0.15mm curved bumps increase the solder contact area by 2.3 times, effectively increasing the number of solder joints. In Comparative Example 3, omitting the bumps reduced soldering reliability by 30%, and contact resistance increased from 8mΩ to 25mΩ (ASTM B571 test).

[0118] High temperature resistance and fatigue resistance

[0119] During high-temperature testing at 200°C, the resistivity of Example 1 increased by only 1.5%, while that of Comparative Example 4, lacking AgNi10 protection, increased by 50%. After 1,000 cycles of mechanical friction, the protrusion structure retained 100% (ISO1639 test). However, in Comparative Example 2, delayed annealing resulted in residual stress embrittlement and a 40% structural collapse.

[0120] 3. Optimization of electrical contact performance and service life

[0121] Functional synergy of AgNi10 alloy layer

[0122] The 2-5μm-thick AgNi10 layer combines high conductivity (Ag-based conductivity ≥ 38MS / m) with arc erosion resistance (Ni particles reinforce the hardness to HV120). Compared to the uncoated comparative example 4, arc erosion is reduced by 60%, and the contact resistance increase after 100,000 on-off cycles is less than 10% (conventional AgCuP surfaces experience an increase of up to 50%).

[0123] Anti-corrosion advantage: Salt spray test (ASTMB117, 48 hours) shows that the surface corrosion rate of the AgNi10 layer is only 0.02μm / h, which is 1 / 5 of that of AgCuP, making it suitable for high-reliability components in humid environments.

[0124] Contact optimization of special-shaped structures

[0125] The curved raised design increases the effective contact area by 30%. According to ASTM B571 testing, the contact resistance remains stable below 8mΩ, a 30% reduction compared to a flat strip structure. This design simulates the principle of "multi-point support," reducing local current density at the contact point and preventing surface burns caused by spark discharges.

[0126] 4. Process compatibility and mass production advantages

[0127] Continuous production integration

[0128] The integrated process of online annealing and profiled roller die rolling enables continuous roll-to-roll production (strip speed 5-8 m / min), increasing production capacity threefold compared to traditional batch processes. In Example 1, the 0.8 mm thick strip, after hot rolling, annealing, and rolling, achieved a dimensional accuracy of ±0.01 mm, meeting the processing requirements for precision electronic components.

[0129] Universality of Material Gradient Design

[0130] The three-layer composite structure (AgNi10-Cu-AgCuP / AgCuZn) can adjust parameters according to the application scenario: for example, by replacing the bottom solder layer with AgCuSn alloy, the melting point is reduced to 580°C, making it suitable for thermal sensors; when the top coating thickness is increased to 5μm, the arc resistance life can be extended by another 1.5 times.

[0131] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A process for manufacturing high-weldability special-shaped contact strips, characterized in that: include: S1. Pre-treating the composite surfaces of the Cu strip and the AgCuP alloy strip or the AgCuZn alloy strip respectively; S2. Laminating the pretreated Cu strip with the AgCuP or AgCuZn alloy strip, and hot rolling the strip at a temperature of 480-520° C. and a pressure of 800-900 MPa, with a total reduction of 35%-45%; S3. Immediately after hot rolling and lamination, perform online annealing: treat at 650±10℃ for 60-90 seconds in a protective atmosphere; S4, subjecting the annealed composite strip to a wire drawing and reducing process, and then precision rolling using a special-shaped roller die to form a special-shaped strip having a raised contact structure; S5. Compounding an AgNi10 alloy layer on the surface of the raised contact.

2. A process for manufacturing a high-weldability special-shaped contact strip according to claim 1, characterized in that: The pretreatment in step S1 includes sandblasting roughening and ultrasonic cleaning of the composite surface. After the treatment, the roughness Ra of the composite surface is 1.0-1.5 μm.

3. The manufacturing process of a high-weldability special-shaped contact strip according to claim 1, characterized in that: The online annealing in step S3 is carried out in a continuous annealing furnace, the strip travel speed is 5 to 8 m / min, and the protective atmosphere is argon with an oxygen content of ≤50 ppm.

4. The process for manufacturing a high-weldability special-shaped contact strip according to claim 1, characterized in that: The special-shaped rolling in step S4 includes two stages: The first stage: rolling the composite strip into a flat strip; The second stage: an arc-shaped raised structure is rolled out on the edge of the strip through a special-shaped roller die, with a raised height of 0.1 to 0.15 mm.

5. The manufacturing process of a high-weldability special-shaped contact strip according to claim 1, characterized in that: In step S5, an AgNi10 alloy layer is formed by electroplating or magnetron sputtering, with a thickness of 2 to 5 μm.

6. A highly weldable special-shaped contact strip, produced by the process according to any one of claims 1 to 5, characterized in that: Contains three-layer composite structure and functional features: Top contact layer: AgNi10 alloy layer provided on the top surface of the strip, serving as the electrical contact functional interface; Intermediate substrate layer: The Cu layer located below the AgNi10 layer, which performs the core conductive and mechanical support functions; Bottom soldering layer: AgCuP or AgCuZn alloy layer compounded on the bottom surface of Cu layer, the bottom surface of which is processed with arc-shaped convex structure with a height of 0.1 to 0.15 mm, and the convexity is in direct contact with the solder.

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