Formation and Growth Mechanism of Nano-Thin Cu6sn5 Films in Sn/Cu and Sn-0.1aln/Cu Structures Using Laser Heating

The reaction between Sn and metal substrate can form intermetallic compounds (IMCs) to realize the metallurgical interconnection in electronic packaging, however, little is known about the formation and growth of nanoscale IMCs. In this paper, we have fabricated the Sn/Cu and Sn-0.1AlN/Cu structure using laser soldering under different laser power (200W, 225W, 250 W) and heating time (2s, 3s, 4 s). The results show clearly that the formation of nano-Cu6Sn5 films is feasible in the laser heating (200w and 2s) with Sn/Cu and Sn-0.1AlN/Cu system, the nano-Cu6Sn5 films with thickness of five hundred nanometers and grains with seven hundred nanometers 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 nm to 2025.8 nm as the laser heating time and the laser power extended. Nevertheless, due to the adsorption of nanoparticles, doping AlN nanoparticles can slow down the growth rate of Cu6Sn5 films in Sn solder joints. The formation of nano-Cu6Sn5 films can provide a new method for nano-film development.