The Shap-design Of CuCGA Solder Joints And The Reliability Analysis

The worldwide ban on lead containing products has made the microelectronics industry incorporate ‘Lead(Pb)-Free’ alternatives in its components, solders and pro- cesses. In order to replace conventional high lead ceramic column grid array(Cu CGA) packaging, IBM developed Cu CGA packaging. The Cu CGA consists of an annealed and tin-plated copper column in place of a high lead(10Sn/90Pb) solder column and Pb-free Sn/3.9Ag/0.6Cu(SAC) solder ?llets in place of eutectic solder ?llets. The ceramic substrate side solder ?llet is the higher melting Sn/18 Ag solder to maintain the packaging hierarchy. Like the CCGA, the Cu CGA offers a high reliability packaging solution without compore mising on the electrical and thermal performances.In this study, we have improved Cu column’s shape by making the two bottoms of copper column into funnel-shape. Based on the reliability evaluation of interconnect, we established three-dimensional models of the double funnelshaped Cu CGA and analysed the influence of length-diameter ratio on strain distribution of double funnel-shaped Cu CGA solder joint through finite element analysis software. The Cu CGA was investigated under the shearing load. The simulation result indicate that after the two bottoms of Cu column made into funnel-shape, the maximum strain is away from solder section, where the properties is poor. Whereas the stress-strain is mainly undertaken by Cu column of good property, thus prolonging the service life of solder joints. For double funnel-shaped welding column, the solder joint of strain reducing with the heigh of copper colum decreased.We have improved Cu column’s shape by making the two bottoms of copper column into funnel-shape. The Cu CGA package is completed 3×3 column interconnections. Through the shear load analyzed the relatiaonship of stress and strain under the same height of Cu colum.The result show that the convel both conventional Cu CGA and funnel-shaped copper column Cu CGA had goog welding property. The strain of interconnect of conventional Cu CGA or funnelshaped copper column Cu CGA was also compared respectively under different length-diameter ratio.And the peak strain was slightly increased with the height of column decreased.