In this paper, there are two major investments consisted of ¡§Failure Mechanism of Inner Lead Au-Sn Bonds in Tape Automated Bonding (TCP) Packages¡¨ and ¡§Cu Wire bond microstructure analysis and failure mechanism¡¨. In view of the advantages of low cost, simple manufacturing process and significant miniaturization in size, TCP technology is widely applied in consumer electronic products. Inner lead bonding (ILB) process is especially crucial for the production of high quality TCP packages and components. The ILB process is extremely dynamic since the bonding time is around 0.2 second to complete the thermo-compress and soldering processes. The composition of liquid pool varied with the bond temperature and pressure and is crucial to exhibit different structure. One type of unusual failure bond happened during the process parameters optimization. ILB joints microstructure was examined by electron microprobe (EPMA) for detail phase analysis. The phase formation sequence of normal and failure bonds can be explained from the Au-Sn-Cu ternary phase diagram and thermo-chemistry data of Au-Sn binary. According to Part I study, the hypo-eutectic composition (<30 at% Sn) liquid pool could maintain the normal ILB bonds. And the hyper-eutectic composition (>30 at% Sn) has the potential risk to form this unusual failure bond. In the Part II study, copper wire bonding samples were aged at 205¢XC in air from 0 h to 2000 h. It was found that the bonding of a Cu wire and an Al pad formed Cu9Al4, CuAl, and CuAl2 intermetallic compounds, and an initial crack was formed by the ultrasonic squeeze effect during thermosonic wire bonding. The cracks grew towards the ball bond center with an increase in the aging time, and the Cl ions diffused through the crack into the ball center. This diffusion caused a corrosion reaction between the Cl ions and the Cu-Al intermetallic phases, which in turn caused copper wire bonding damage.