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Solutions for Delamination & Cold Joints in Copper Foil Flexible Connectors by Polymer Diffusion Welders
Jul 18,2026
Copper foil flexible connectors are core conductive components for new energy batteries, energy storage equipment and electric control systems. Polymer diffusion welding is widely adopted for its flexible conductivity and excellent heat dissipation. This technology realizes solder-free, low-resistance and high-strength copper joints via atomic metallurgical bonding. However, delamination and cold joints are the most frequent quality defects in mass production, with targeted solutions as follows.
I Core Mechanism of Two Defects
Delamination and cold joints share similar root causes — insufficient interlayer atomic diffusion. Their key differences:
1.Delamination: Caused by interlayer gaps, oxide contaminants or stress concentration, leading to weak interlayer bonding that separates under external force.
2.Cold joints: Triggered by mismatched temperature & pressure, atomic diffusion fails to reach critical threshold, only partial weak adhesion forms without effective metallurgical bonding.
II Solutions to Delamination
1.Optimize interlayer pre-treatment: Remove oxide film, oil and dirt thoroughly to eliminate gaps and oxidation risks at source.
2.Adjust welding parameters properly to guarantee full interlayer atomic diffusion.
3.Optimize welding processes to relieve interlayer stress concentration.
4.Inspect equipment regularly: Check pressure transmission and heating assemblies to ensure uniform heat & pressure delivery.
III Solutions to Cold Joints
1.Set precise temperature & pressure matching copper material and size to avoid insufficient diffusion from extreme parameters.
2.Strict interlayer cleaning & tight lamination; eliminate impurities/gaps to smooth atomic diffusion.
3.Standardize operation procedures to prevent foil shifting and poor fitting caused by human error.
4.Complete full post-weld inspection to screen out cold joint products timely.
IV General Prevention & Control Measures for Both Defects
1.Raw material control: Adopt uniform, oxide-free, undamaged copper foil.
2.Scheduled equipment maintenance: Inspect heating elements, pressure sensors and temperature controllers weekly; calibrate parameters monthly; replace aged electrodes/fixtures quarterly; clean heating chamber & gas pipeline to maintain stable operation.
3.Operator training: Regular skill training covering pre-treatment standards, parameter setting and welding processes for copper flexible busbars.
4.Closed-loop management: Record parameters, pre-treatment status and test results; trace root causes of delamination/cold joints and optimize processes accordingly.
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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