Experimental Research on Silver Alloy Wire Bonding as an Alternate for Bare Copper or Gold Material in Conventional Wire Bonding
摘要
In Micro systems packaging technology, basically wire bonding is an electrical interconnection technique between the chip and lead frame (substrate) under the application of temperature, ultrasonic energy and bond force. The most common material used in the wire bonding process is gold (Au). It has the advantage of a fast bonding process and exhibits good electrical properties but is highly expensive. Many investigations are carried out to replace conventional wire bonding with new materials. Copper (Cu) was one such alternative in the wire bonding process. But the main drawback is it gets oxidized very easily and leads to poor bonding. Palladium-coated copper (Pd Cu) is replaced by Cu, which plays an important role in the prevention of oxidation. High electrical resistivity and high hardness of Pd Cu are major challenges when compared with Silver (Ag). Hence Ag stands as another competitor against Au in wire bonding, where extensive research is carried out for its reliability. This paper compares the results of copper, palladium-copper and silver alloy with that of gold from its optimized parameters and characterization- via Mechanical, Electrical and Scanning Electron Microscope (SEM) results.