Advanced surface plating on the organic FC-BGA package

Abstract

Electric components and devices have become high density more and more because of demands for high performance. Nowadays, electroless surface plating is often applied to the surface finish of substrate land patterns for soldering and interconnections due to the enhancement of the wiring design on the mounting hoard, which leads to the shrinkage of the devices. In some cases, though, electroless plating causes weak solder joints on the external terminals of electric devices and packages. The key issue on the developed organic FC-BGA (Flip-chip Ball Grid Array) packaging process is to achieve the ball attach strength on the substrate lands with electroless nickel and immersion gold plating. It was confirmed that the root cause of the weak strength was the existence of the phosphoric enrichment layer with the detailed analysis. Additionally, regarding with the new approach to solve the weak solder joint, the DCNP (double-layered constructed nickel plating) was effective in preventing the progress of the phosphoric enrichment layer.