2007 Volume 25 Issue 1 Pages 51-58
Al/Cu bonding in the air can be accomplished at the temperature range between eutectic temperature of Al-Cu system and melting point of Al. The change of microstructure in Al/Cu bond was investigated by SEM observation and EPMA analysis. The observed specimens were obtained by the difference of displacement of bonded specimen. Mushroom shape of L is observed in Al side at the first step of the initial stage of bonding process. The phase in Cu side begins to be observed significantly at the second step of the initial stage. The time difference is brougt by the difference of each diffusion coefficient. The ratio of bonding area of this bonding method depends on the formation ratio of the phase in Cu side. L phase begins to be removed by the bonding load after the initial stage. L, α, θ(Al2Cu) and η2 (AlCu) are observed in the bond as the major microstructure of the bond at room temperature. Formation mode of the pre-existed θ layer affects the shape of next θ grain formed from liquid. Al oxide film can glow by the absorption of oxygen from the resolved Cu oxide film. The diffusion route is made by the separation of Al and Cu oxide film at the first step of the initial stage. Reaction diffusion occurs through the area where the separation of oxide film occurs and forms liquid in bond during this bonding process.
