In-situ microscale FIB cold welding of Al and Cu

As manufacturers of electrical devices push for improved performance, enhanced functionality, cost-efficiency and sustainability, the development of electronics increasingly depends on multi-material metal components [1, 2] with a trend in product miniaturization [3]. Hence this evolution calls out for development of new joining methods. A welding setup in the focused ion beam has been developed. The setup consists of a custom-made Cu micromanipulator needle, which is inserted into a pre-made hole in an Al slab [4]. A bonded interface is created by causing severe plastic deformation and formation of excess vacancies during insertion, while keeping the temperature low (<100°C) [4]. The goal is to induce vacancy enhanced diffusion and get a strong bond between the metals, with limited formation of inter-metallic layers [5, 6]. This project aims to investigate welds made using this procedure by different process parameters, like different strain rates. The welds are analyzed by systematic cross-section images by the focused ion beam, and transmission electron microscopy will be used to perform a detailed characterization of the joints, with focus on both chemical composition and phase identification.