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Wire bonding is a key technique for electrical interconnections between integrated circuit (IC) and the metal frame or printed circuit board (PCB). One of the most common wire bonding system is bonding of the Au wire to Al metallization, however, Cu wire is being considered as replacement for Au wire due to surge of Au price. This research focuses on the formation and growth behavior of Cu/Al intermetallic compounds (IMCs). In order to investigate IMC growth after 30, 60 and 120 min of aging at 270, 300 and 330°C, cross-section of Al, Cu and Cu/Al IMCs were examined by scanning electron microscopy (SEM). The results showed that the consumption of the Al layer is more rapid than that of Cu layer, and that after 120 min at 330°C the Al layer is entirely consumed. The formation of three distinct Cu/Al IMC layers was observed. Scanning transmission electron microscopy (STEM)/energy-dispersive X-ray spectroscopy (EDS) was used to identify the three IMC layers formed at the interface. In addition, the IMC compositions were identified by selected-area diffraction pattern (SAD). These were CuAl, Cu 3 Al 2 and Cu 9 Al 4 . Also, the activation energies of Cu/Al IMC growth were obtained from an Arrhenius plot.

In this study, 60 solder compositions were examined in an effort to improve the integrity against impact loads of the solder joints on an electroless Ni-P/Au surface finish. The Ag, Cu, and Ni contents in the Sn-based solder varied from 0 to 4.5 wt%, 0 to 2.0 wt%, and 0 to 0.05 wt%, respectively. Impact shear tests were performed to investigate solder joint integrity after solder ball reflowing, after reflow soldering twice more, after storage at room temperature for 168 hours, and after storage at 150°C for 1,000 hours. According to the results, the Ag content should be as low as possible, the Cu content should be from 0.5 to 0.7 wt%, and the Ni content should be as high as possible. The Ag and Ni contents should be determined in consideration of the wettability and the board-level reliability of the solder joints.

Recently, there have been many developments on power devices to improve their functions. Especially, the junction temperature of power modules that equip SiC (Silicon Carbide) chips will be higher than 200 °C as current densities are too high, and new electronic packaging technologies shall be developed to meet higher temperature and higher power cycle durability requirements. In order to meet these requirements, in the present study, we propose Cu wire, Cu ribbon and Cu connector between Cu wirings of the substrates and investigate their feasibilities, including electrical resistances, footprints of bonding area, and bonding reliability under accelerated stress test, respectively.