THE ALTERNATIVE TO ULTRASONIC WIRE BONDING
When making interconnections in battery modules, laser welding is faster than traditional wire bonding. For cylindrical cells, busbars can even be welded directly to the cells instead of connected via wires, diminishing by half the number of welds in the module. Single-mode fiber lasers also provide an excellent and controlled weld penetration with minimal spatter and reduced heat.
Whereas ultrasonic welding systems use sonotrodes specifically designed for each application and limited to simple shapes, the Laserax welding systems can be adjusted on the fly to create various welding patterns and sizes.
Overview of battery welding applications:
- Materials: Copper, Nickel, Aluminum, Nickel-Plated Steel and Stainless Steel.
- Types of cells: Pouch, cylindrical and prismatic welding
- Battery components: Can, terminals, foils, busbars, cell cases, safety vents, cover plates
The Fastest Welding Process
When making cell-to-busbar connections, ultrasonic wire bonding typically takes between 500-1000ms per weld. Laser welding is much faster because it involves fewer, smoother mechanical movements: only ultra-fast mirrors located in the laser head need to be moved to position the laser beam. This drastically reduces the positioning time for each weld. When integrated with our robots, the average welding time including mechanical movements between cells can reach values under 100ms per cell.
|Busbar Thickness*||Laser Power||Resistivity (µΩ)||Strength (N)||Time (ms)||Depth of Penetration into Positive Tab (µm)|
* The positive tabs were 500-micron thick.
Because of our faster welding speed, a single laser welding machine can easily work like 10 ultrasonic wire bonders. This minimizes the number of machines needed in production facilities, allowing you to:
- Save square footage
- Save energy
- Reduce maintenance
Cylindrical cells: from 4 welds to 2 welds
Whereas ultrasonic wire bonding typically requires 4 welds per cell, laser welding only needs 2. This provides several benefits:
- A larger contact area
- Half as many potential failure points
- One weld carries all the current (higher current per weld)
- Less mechanical stress transferred to the module
- Smaller resistance (lower heat & electrical loss)
- Better current distribution
- Better heat transfer from cells to busbar conductors
A pulsed laser welding process
Continuous lasers have traditionally been used to perform industrial laser welding because they allow deep penetration into the material. But when it comes to battery welding, pulsed lasers offer important advantages:
- Stronger welds with lower resistivity
- Minimal depth of penetration (<100µm)
- Minimal heat affected zone
When you work with Laserax, laser experts optimize the optical components and parameters of the laser for your specific application. Our unique processes generate better results than what other pulsed lasers have shown in the past. More specifically, we obtain:
- Smaller heat affected zones
- Shallower/less intrusive welds
Joining method by cells type format