High-speed laser plating on Cu leadframe using Ag nanoparticles

The present paper proposes high-speed laser plating for forming wire-bonding pads on a Cu leadframe using Ag nanoparticles. Various aspects of the proposed method have been investigated, including the shape and surface roughness of the lead, experimental set-up, multistep printing, laser-plating parameters, quality of the sintered film with FIB-SIM and LSM, and wire bondability between the Ag pad and an Au wire with a pull test. Experimental results with Ag nanoparticles were compared with those of furnace curing and electroplating. As a result, superiority of the laser plating process has been confirmed from the viewpoints of sintering time (millisecond order per lead), material consumption (picoliter order), the necessity of pre- and post-processing, wire bondability, thermal damage to the pad and substrate, and environmental protection. In particular, novelty lies in the implementation of drop-on-demand laser plating on the specially designed round lead.