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Differences Between Welding Processes of Copper Flexible Connectors for New Energy & Power Industries Using Polymer Diffusion Welders
Aug 14,2026
Polymer diffusion welding is the mainstream solder-free technology for multi-layer copper foil flexible connectors. Metals fuse via atomic diffusion, delivering low-resistance, tightly bonded joints that resist delamination. However, applying identical parameters to new energy and power copper connectors easily causes brittleness, loose bonding, long-term overheating and unstable internal resistance. Distinct operating conditions and performance standards demand differentiated welding processes.
I Differences in Working Conditions & Core Requirements
1.New Energy Copper Flexible Connectors
Mainly applied to batteries, energy storage and charging piles, made of stacked ultra-thin copper foils. Subject to frequent large current switching, long-term vibration, alternating hot & cold cycles and repeated bending. Core demands: superior flexibility, anti-fatigue performance, no cracking or delamination, stable internal resistance.
2.Power Industry Copper Flexible Connectors
Used in distribution cabinets, transformers and substations, fabricated from thicker copper foils with high overall rigidity. Bear steady heavy current continuously and instantaneous short-circuit high temperature. Core demands: fully compact welds without voids, rigid structure, high temperature resistance and no overheating under long energization.
II Key Welding Process Differences
1 Welding Temperature
1.New energy connectors: Medium-low temperature welding with strict overheating control. Excess temperature coarsens copper grains, embrittles material and peels off coatings, leading to cracking under later bending & vibration.
2.Power connectors: Relatively high welding temperature. Thick foils have poor thermal conductivity and abundant interlayer gaps; high temperature promotes deep atomic diffusion to eliminate hidden cold joints & micro-pores.
2 Welding Pressure
1.New energy connectors: Gradient low-pressure holding. Thin copper foil is soft; high pressure crushes and damages ductility. Low pressure flattens foils and exhausts interlayer air while retaining flexibility.
2.Power connectors: Constant high-pressure welding. Thick foils have thick oxide layers and large gaps; high pressure compacts layers and breaks oxide films for complete bonding.
3 Constant-Temperature Holding Time
1.New energy connectors: Moderate holding duration. Extended high-temperature holding alters internal copper structure, increasing brittleness and reducing fatigue resistance.
2.Power connectors: Prolonged constant-temperature period to enable full internal atomic fusion of thick foils and eliminate hidden incomplete bonding.
4 Cooling & Forming Process
1.New energy connectors: Slow cooling under sustained pressure. Thin foils are sensitive to temperature difference; rapid cooling or early pressure relief creates internal stress, triggering hidden interlayer cracks that break in service. Full-pressure cooling releases stress and retains flexibility.
2.Power connectors: Looser cooling requirements. After high-temperature pressure holding, cooling speed can be moderately accelerated, prioritizing overall rigidity and flatness for tight assembly without long-term deformation.
III Pre-Work Treatment & Tooling Matching Differences
1.New energy connectors: Thoroughly remove oil and dust from foils to avoid coating damage & local cold joints. Gentle clamping fixtures to prevent thin foil extrusion & misalignment.
2.Power connectors: Ensure neat, aligned plate end faces; moderate flattening extrusion allowed. Rigid clamping jigs guarantee zero offset and full lamination of thick foils.
IV Common Defects & Root Causes
1.New energy connectors: Coating blackening & peeling, brittle cracking upon bending, interlayer delamination, fluctuating resistance. Causes: excessive temperature/pressure, overlong holding, rapid cooling or premature pressure relief generating stress.
2.Power connectors: Inner-layer cold joints, incomplete edge fusion, temperature rise under current, loose structure. Causes: insufficient temperature/pressure, short high-temperature holding, residual interlayer air & gaps.
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Wuxi HAIFEI Intelligent Equipment Co., Ltd.
Wuxi HAIFEI Welding Equipment Co., Ltd.
Add: 28 Shuiyun Road, Yuecheng, Jiangyin, Jiangsu Province, China. (Postal Code: 214404)
Mobile: +86 18915302352
Email: wushijie@jshaifei.com