Using Nanoparticles and Carbon Nanotubes to Enhance the Properties of a Lead-free Solder
S.M.L. Nai, Y.D. Han, H.Y. Jing, C.M. Tan, J. Wei, M. Gupta
Singapore Institute of Manufacturing Technology, SG
Keywords: nanoparticles, carbon nanotubes, composites, lead-free solder
Abstract:Solders are used in various levels of electronic assembly sequence, whereby good electrical, thermal and mechanical performances of solder are necessary. With miniaturization of devices, diverse functional requirements and ever-stricter operating environments of devices, the development of new interconnection materials with enhanced service performance is necessary. An attractive and viable method of enhancing the performance of a solder is to intentionally introduce nano-size, non-coarsening second phases to a conventional solder alloy, so as to form a nanocomposite solder. This study highlights the effects of nanoparticles and carbon nanotubes as reinforcement on the physical, thermal and mechanical characteristics of a lead-free solder (Sn-Ag-Cu). The nanocomposite solders were fabricated using powder metallurgy technique followed by extrusion. Characterization results convincingly established that composite technology coupled with nanotechnology in electronic solders can lead to simultaneous improvement in thermal performance (in terms of better thermal stability with increasing amount of nano-size reinforcements) and mechanical performance (in terms of better 0.2% yield strength (13 - 23% increase) and better ultimate tensile strength (17 – 34% increase)). There was also no compromise on the melting temperature and electrical performance. With the addition of nano-size reinforcements, better wettability (in terms of lower contact angle) of the nanocomposite solders was also observed. These advanced interconnect materials will hence benefit the microelectronics packaging and assembly industry. An attempt is made in this study to correlate properties of the resultant nanocomposite solders with increasing presence of nano-size reinforcements.