In busbar manufacturing, developers are faced with a central challenge: creating connections that are both highly electrically conductive and extremely resilient mechanically — permanently, reproducibly and in short cycle times.
Whether in battery modules, power electronics or DC distributors, busbar connections must be able to safely withstand tensile forces, vibrations and thermal cycles. Failure of the connection can lead to increased contact resistance, heat generation or even system failure.
Ultrasonic welding is a technology that is designed precisely to meet these requirements and has proven its worth particularly where maximum strength is required.
Why strength is a critical factor for busbars
Busbars are subjected to high mechanical and thermal stresses, for example through:
- Tensile loads during contact or due to vibration
- Shear forces during thermal expansion or dynamic load changes
- Assembly influences and repeated mating cycles
- Long-term micromovements, for example in vehicle applications
The key to a permanently safe connection is therefore:
- High mechanical resilience, especially in shear and peel direction
- Large-area, homogeneous contact for optimum force distribution
- Stability over the entire service life
Particularly strong busbar connections of 5000 Newton and more
The ultrasonic process is based on a combination of high-frequency vibration and defined pressure. This mechanically breaks up the oxide layer on the contact surface and transforms the material into a plastic condition - without any melt. The result is a material-locking connection that remains stable even under high loads.
This connection holds up to enormous forces. Depending on the nature and thickness of the busbars, 5000 N and more can be achieved. This makes the connections significantly more robust than with comparable processes such as soldering or laser welding.
Another advantage is that the welding surface can be flexibly designed - from localised to large areas. This allows the load to be distributed evenly over several layers or complex geometries. This is a decisive factor for the quality of the joint, especially for wide or multi-layer busbars.
With our Ultrasonic Power Stack 12 kW, welding forces of up to 10,000 N are available. This provides sufficient power to reliably join even large copper-aluminium connections with a high material thickness.
This not only enables high strengths, but also process safety welding in short cycle times even with demanding bimetal configurations.
Conclusion: ultrasonic welding makes reliable connections - even under maximum load
When busbar connections have to fulfil the highest mechanical and electrical requirements, ultrasonic welding is the right choice. The process is fast, reliable and highly customisable — both in terms of geometry and process performance.
The most important advantages at a glance:
✅ Mechanically high-strength connections, even with mixed metals
✅ Welding forces of up to 10,000 N with the Herrmann Power Stack 12 kW
✅ Large configurable welding zone for optimum force distribution
✅ No brittle phases, no solder, no heat deformation
✅ Stable connections in shear and peel direction
✅ Reproducible, automated, fast
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