Developing new joining materials for low-temperature electronics assembly

Abstract : The present work focuses on a new kind of lead-free joining method for surface-mount technology based on precursor chemistry. The interest of metal oxalates as new soldering materials for die attachment (1st level packaging) was previously demonstrated with silver oxalate. The thermal decomposition of metal oxalates under controlled atmosphere can be used to produce small metal particles below their melting point. These particles are found to be in a highly active particulate form. First experimental studies are focusing on several metal oxalates (tin oxalate and bismuth oxalate) to assess their suitability for low-temperature metal particle production. The main work is dealing with controlled chemical precipitation synthesis and characterization of the compounds as well as study of the properties of decomposition solid products (powder X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and thermal analyses under different atmospheres).