Laser welding of copper and copper alloys

We have developed a laser hermetic sealing technique that combines nickel plating with laser welding for copper and copper alloy bellows for general purpose large‐scale computers. Laser welding of copper has been difficult because of copper's high thermal conductivity and reflectivity. However, laser welding nickel‐plated copper results in deep penetration. To avoid corrosion induced at the dissimilar metal contact between nickel and copper, the nickel‐plated copper was heat‐treated before welding to obtain a nickel‐copper solid solution. Then, the optimum plating thickness and heat‐treatment conditions were determined. A 10 μm‐thick nickel plating, heat‐treated for 1 h at 1000°C was found to be best suited to laser welding. These conditions make the laser weld of copper and copper alloy strong. Tests indicate that this technique is suitable for laser welding copper and copper alloys.