Formation and growth mechanism of thin Cu6Sn5 films in Sn/Cu and Sn-0.1AlN/Cu structures using laser heating.

Purpose: The purpose of this study is the formation and growth of nanoscale intermetallic compounds (IMCs) when laser is used as a heat source to form solder joints. Design/methodology/approach: This study investigates the Sn/Cu and Sn-0.1AlN/Cu structure using laser soldering under different laser power: (200, 225 and 250 W) and heating time: (2, 3 and 4 s). Findings: The results show clearly that the formation of nano-Cu₆Sn₅ films is feasible in the laser heating (200 W and 2 s) with Sn/Cu and Sn-0.1AlN/Cu system. The nano-Cu₆Sn₅ films with thickness of 500 nm and grains with 700 nm are generally parallel to the Cu surface with Sn-0.1AlN. Both IMC films thickness of Sn/Cu and Sn-0.1AlN/Cu solder joints gradually increased from 524.2 to 2025.8 nm as the laser heating time and the laser power extended. Nevertheless, doping AlN nanoparticles can slow down the growth rate of Cu₆Sn₅ films in Sn solder joints due to its adsorption. Originality/value: The formation of nano-Cu₆Sn₅ films using laser heating can provide a new method for nanofilm development to realize the metallurgical interconnection in electronic packaging. [ABSTRACT FROM AUTHOR]