Development of Advanced Nanocomposite for Micro/Nanosystems Packaging

Abstract

Non-coarsening reinforcements (carbon nanotubes, TiB2, Y2O3 and ZrO2 + 8mol. % Y2O3 particulates) were successfully incorporated into 95.8Sn-3.5Ag-0.7Cu solder, to synthesize new lead-free composite solders. Characterization results convincingly established that composite technology in electronic solders can lead to simultaneous improvement in thermal performance (in terms of lower coefficient of thermal expansion) and mechanical performance (in terms of better microhardess, tensile and creep properties), without compromising on the melting temperature and electrical performance (in terms of no change in electrical resistivity/conductivity). A threshold addition of reinforcements was observed to aid in optimizing the properties of the composite solder. Composite solders reinforced with carbon nanotubes yielded the best overall properties. Isothermal aging studies showed that composite solder joints exhibited lower diffusion coefficient, signifying presence of reinforcements was effective in retarding the interfacial intermetallic layer growth. These advanced interconnect materials will hence benefit the microelectronics packaging and assembly industry.