Electroless nickel/Immersion gold process on Aluminum alloy electrodes

Electronic equipment has changed to have higher performance with minimized in size. This trend required to electronic devices minimization also. Numerous packaging techniques have developed using metal flame, PWB material and plastic tape to mount semiconductor devices on PWB¹⁾. To achieve further high mounting density, the semiconductor device directly solder mounted on package after forming metal bumps on electrode of semiconductor devices. Aluminum alloy is common material for electrode of semiconductor devices, since it has relatively high conductivity, chemically stable and less reaction in semiconductor manufacturing process. However, it needs other meal layer for soldering to form bump on it. Sputtered Ti/Cu layer and electrolytic solder plating is widely used to form solder bump. However, this process requires longer and costly process such as multiple vacuum process, photo image process, etc.