Ultrasonic Welding for Electrical Connections and Batteries

Ultrasonics can be used to safely connect the same and different non-ferrous metals within a very short time. It is mainly used for the connection of conductive non-ferrous and precious metals. These include aluminum, silver, copper and nickel in particular, with aluminum-copper connections accounting for 90% of applications.

Weldable non-ferrous metals are all pure metals except iron as well as alloys (connections of different metals) that have less than 50 percent iron content. Pure ferrous metals cannot be joined with ultrasonics.

Due to the optimal conductivity of the connections and the short welding times, ultrasonic welding has established itself as a joining technology for numerous applications consisting of non-ferrous metals. These typically include:

• Lithium-ion battery (LIB)
• Pouch cells and flexible housings
• Battery management systems
• Wire-terminal
• High-voltage cable
• Busbar / terminal terminal

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Ultrasonic welding is a joining process without additional joining agents. Mechanical vibrations are created by an ultrasonic generator and converter. The welding tool, the so-called sonotrode, transfers these mechanical vibrations to the components.

One joining part vibrates in the longitudinal direction, while the other remains secured in the fixture. Friction breaks up the oxide layer and the parts are welded together at the same time under pressure.

The decisive factor in welding is not the heat generated, which is well below the melting point, but the relative movement of the two joining partners.

Ultrasonic welding of metals has several advantages over conventional welding methods such as crimping or laser welding:

• Speed: The welding process with ultrasonics only takes fractions of a second.
• Reliability: The specification and monitoring of numerous welding parameters ensures precise and reproducible welding results. This is a decisive advantage, especially when welding sensitive and small metal parts, such as in batteries.
• Cost efficiency: Ultrasonic welding does not require any additional joining materials such as solder.
• Sustainability: Ultrasonics welding requires very little energy as it does not use heat to connect metals and does not require the use of chemical tools.
• Safety: Ultrasonic welding produces no sparks or smoke, which makes it safe to work in manufacturing.
• Gentle: Materials are not damaged or deformed outside the defined weld area.

When welding with ultrasonics, the ideal parameters are determined individually for each application via test series in the ultrasonic laboratory. These can be reproduced exactly thanks to the precise process control.

This ensures a safe, reliable process and minimizes scrap rates – and costs – over the long term. 

Up to 150 different welding data can be recorded, saved and exported for each individual welding process. This monitoring is fully automated and ensures seamless digital quality control.

Another advantage of archiving the welding processes: each weld is assigned to a specific component, giving it its own digital fingerprint. This enables complete traceability. 

For example, if a problem occurs with a battery cell later during use, it is possible to check exactly if the welding process was carried out according to the defined specifications or if deviations have occurred. In the case of deviations, other battery cells with the same deviations can also be identified.

Our experienced experts will be happy to show you the advantages of ultrasonic welding for your individual application. 

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