| Now with the rapid development of IC industry, device miniaturization trend made packaging industry a hot focus area in recent years. As the most widely used mode of interconnection, wire bonding is gradually entering the research field of people’s vision in device packaging. In recent years, due to the low cost and good comprehensive performance of materials, copper wire bonding gets more and more attention instead of gold wire. But copper is more chemical actively and hard than gold. Therefore problems may be reserved in the process of interface bonding strength and anti-oxidation. These matters become the main study stream of many scholars. This article will mainly concern pure copper wire and palladium-coated copper wire bonding process during the free air ball formation and the FAB. First the profile sample preparation would be used and then chemical corrosion should be adopted, which would achieve the goal of the grain. Using the high power optical microscope analysis, the grain shape and size on different positions of the FAB and the wire section have been analyzed, subsequently different samples have been compared with the hardness that can be obtained from hardness tests, the grain size and EFO parameters. In addition, the Pd anti-oxidation of palladium-coated copper wire has been investigated. TEM sample preparation and EDX analysis have been used to display the morphology and distribution of Pd on the FAB visually, while Pd weak area of different samples have been analyzed through the chemical etching method, so that the regional shape parameters could be connected regularity with EFO process parameters. Finally, the related theoretical model of FAB has been established, based on the comparison between the theoretical calculation and the experiment data, at last relevant conclusions would be reaped. The Pd coverage analysis has been provided a reference for the parameters and reliability in the following processes. |
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