Conductive materials

Battery Tab and Busbar Welding

A workflow for copper, aluminum, and nickel tab welding parameter planning.

Main variableContact stability

Copper and aluminum respond strongly to clamp force, contact area, and surface condition.

First proofPull + section

Use mechanical check and cross-section together before accepting a tab recipe.

Watch firstExpulsion

Expulsion, local overheating, and inconsistent absorption often define the upper window edge.

Battery tab setup workflow

Step	What to do	Evidence to keep
Material pair	Identify tab, busbar, plating, coating, and stack thickness.	Nickel-plated copper to aluminum behaves differently from bare copper to copper.
Surface and clamp	Clean the interface, lock contact pressure, and prevent sheet lift.	Record clamp force, overlap area, and part flatness for each sample.
Energy window	Trial short high-peak settings against lower peak, longer dwell settings.	Compare expulsion, nugget size, splash, local burn, and electrical resistance.
Inspection	Run peel/pull checks, cross-sections, and resistance measurements where applicable.	Keep rejected settings in the log so the window boundary is visible.

Observed issue	Move first	Check before widening the window
Weak pull strength	Increase nugget size with a small energy increase or lower travel speed/pulse speed.	Check actual overlap, contact pressure, and whether oxide or plating blocked coupling.
Heavy expulsion	Reduce peak energy concentration or shorten the energy rise into the joint.	Inspect clamp flatness and whether one layer lifted before the pulse or seam segment.
High electrical resistance	Review surface cleanliness and interface collapse before adding more heat.	Section the weld to confirm real bonded area instead of using pull force alone.
Heat damage to separator or nearby layers	Reduce total heat input, improve local heat sinking, or tighten the energy footprint.	Record distance to sensitive layers and fixture temperature after repeated samples.

Checklist item	Minimum record	Decision supported
Mechanical check	Peel/pull result, failure mode, and sample count.	Confirms whether the bond survives the required handling or load case.
Cross-section	Nugget width, penetration into each layer, splash, and bonded interface.	Confirms whether the weld mode matches the electrical and mechanical target.
Electrical result	Contact resistance or voltage-drop record where relevant.	Prevents accepting a strong but electrically poor joint.
Fixture state	Clamp force, anvil/contact condition, and maintenance state.	Many “parameter problems” are actually fixture-repeatability problems in tab welding.