High-performance silicon-metal laser welding resisting extreme conditions

Reliable material joining is essential for countless industrial applications. While femtosecond laser welding provides a route beyond conventional bonding methods, demonstrations of silicon-metal joints are rare due to nonlinear propagation effects and have so far been limited to shear joining strengths of a few MPa. Here, we demonstrate high-strength silicon-Kovar laser welding using sub-nanosecond pulses. By optimizing the focal position, the welding pattern, the laser polarization, and the metal roughness, remarkable shear joining strengths up to 15.8 MPa are achieved. The silicon-metal joints withstand temperatures of up to 500 °C and are hermetically sealed. Together with the remarkable strength values, the resistance to harsh environments underpins the applicability of silicon-metal welding in various fields including aerospace, nuclear science, and metallurgy.