Laser welding copper and copper alloys

Abstract

We have developed laser hermetic sealing technique which 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, we heated the nickel plated copper before welding to obtain a nickel-copper solid solution. We then determined the optimum plating thickness and heating conditions. A 10 μm thick nickel plating, heated 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.We have developed laser hermetic sealing technique which 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, we heated the nickel plated copper before welding to obtain a nickel-copper solid solution. We then determined the optimum plating thickness and heating conditions. A 10 μm thick nickel plating, heated 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.