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Solutions for Delamination & Cracking of Copper Foil Flexible Connectors Welded by Polymer Diffusion Welder
Aug 07,2026
Copper foil flexible connectors are core connecting components in new energy batteries and power energy storage industries. Polymer diffusion welders serve as their primary welding equipment, which can realize tight bonding of copper foil without filler metal and suit mass production. Delamination and cracking of copper foil degrade the conductivity and structural strength of flexible connectors, bringing hidden safety hazards such as equipment short circuits and increasing rework & material costs. Such defects are mainly caused by improper process parameters, abnormal equipment conditions, poor incoming material quality and non-standard operation specifications.
I Manifestations & Hazards of Delamination and Cracking
1.Manifestations: Gaps easily form between copper foil layers which can be peeled off effortlessly, accompanied by blackening and oxidation in some cases; cracks may appear on welding zones and even run through the whole welding surface in severe cases; local delamination & debonding may occur, or the copper foil becomes brittle and fractures upon bending after welding.
2.Hazards: Reduced conductive area leads to severe heat generation during operation and shortened equipment service life; weakened tensile & bending resistance makes the connectors prone to breakage and circuit interruption; gaps trap water and dust to accelerate oxidation and may cause short circuits or even fires in serious cases; batch defects waste raw materials and prolong production cycles.
II Root Causes of Delamination & Cracking
1.Improper process parameters: Excessively high/low temperature, excessive/insufficient pressure, inadequate/excessive holding time, insufficient preheating or rapid cooling all trigger copper foil delamination and cracking.
2.Abnormal equipment status: Uneven heating & pressure output, inaccurate temperature measurement, worn fixtures, positioning deviation, residual contaminants on equipment surface contaminating copper foil.
3.Unqualified incoming materials: Uneven copper foil thickness, surface oxidation & impurities, impure base metal, mismatched layer thickness combinations, unsupportive auxiliary materials hinder copper foil bonding and result in delamination.
4.Non-standard operation & environment: Operators fail to fully clean copper foil, misplace sheets without full compaction or adjust parameters arbitrarily; humid, dusty or corrosive welding atmosphere accelerates copper foil oxidation and aggravates cracking.
III Remediation & Prevention of Delamination & Cracking
(1) Remediation of Existing Defects
Slight delamination: Clean surface oxidation and contaminants, readjust parameters and re-weld then test bonding strength.
Moderate cracking: Peel cracked areas, clean thoroughly, fill with copper foil of identical specification then re-weld and grind.
Severe cracking, overall brittleness or large-area delamination: Scrap the workpiece completely and trace root causes.
Notes for repair: Fully clean copper foil, adjust parameters gradually; conduct quality inspection after rework.
(2) Source Prevention Measures
1.Optimize process parameters: Set appropriate temperature, pressure and holding time based on copper foil layers & thickness; implement complete preheating and slow cooling to avoid stress concentration.
2.Regular equipment maintenance: Calibrate machines periodically, remove contaminants daily, inspect and replace worn parts, monitor equipment status and handle anomalies timely.
3.Strict incoming material inspection: Adopt qualified copper foil with clean surfaces and matching auxiliary materials; match layers & thickness reasonably and test all incoming goods before storage.
4.Standardize operation & environment: Clean and stack copper foil as required without random parameter changes; maintain dry, ventilated welding workshops and store copper foil hermetically to prevent oxidation & dampness.
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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