A new bond failure wire crater in surface mount device

A new failure wire crater was studied in surface mount devices. It is defined as a peeling-off phenomenon of the wire ball from the Si substrate or insulator when soldering heat stress is present. It only occurs when the package absorbs a significant amount of water before soldering. To analyze this phenomenon, conditions of water absorption, soldering heat stress, wafer process (metallization and insulator materials) and assembly process (wire bonding) were investigated. From these results, it is found that cratering occurs when the Si nodules of Al-Si metallization damage the insulator at wire bonding.<>