Calculating Intermetallic Growth Rates to Set Stamping Tooling Replacement Intervals
Calculating dynamic intermetallic growth rates establishes press stroke limits that prevent tab burrs and optimize die replacement intervals.
Clad Tab Stock
Meaning
Multi-layer composite metal strips provide the electrical and mechanical bridge between cell terminals and busbars. Using clad tab stock prevents the galvanic corrosion and high electrical resistance that typically arise when joining dissimilar metals. This material usually consists of aluminum and copper layers bonded together under high pressure.
Designers utilize these composite strips to facilitate reliable laser or ultrasonic welding in battery pack assembly.
Bond Integrity
Cold-roll bonding represents the primary manufacturing process for joining these distinct metallic layers. Through this method, clad tab stock achieves a true metallurgical bond without the presence of brittle intermetallic phases. This structural continuity ensures that the strip withstands repetitive vibration during vehicle operation.
Procurement specifications must dictate the minimum peel strength required to prevent delamination during terminal bending.
Joint Protection
Electrochemical cell terminals require careful material matching to avoid galvanic cells at the contact points. Utilizing clad tab stock allows a copper anode tab to connect to an aluminum busbar without forming a high-resistance oxide layer. The mechanical joint remains stable under thermal cycling, which is a major factor in maintaining a low pack-level voltage drop.
This stability directly reduces localized heating at the connection points during fast charging. It also prevents the moisture-driven corrosion that occurs in humid pack environments when bare metals touch. Consequently, pack failures from terminal separation or joint degradation are minimized.
Electrical Performance
The thickness ratio of the constituent metals determines the overall electrical and thermal conductivity of the tab. Sourcing teams specify these ratios based on the continuous current requirements of the cell. A thicker copper layer lowers the bulk resistance but increases the weight of the assembly.
For this reason, optimizing the metal distribution is a standard trade-off in pack design.