Optimization of nickel thickness on substrate for TBGA using SAC387 solder material

Abstract

The purpose of this paper is to discuss the effect of Nickel (Ni) thickness on lead free solder joint material for tape ball grid array (TBGA) application. In this study, four different level of Nickel thickness were chose that is 3um, 4um, 5um and 6 um. Ball pull testing was used to assess the solder joint performance at time zero, after multiple reflow and high temperature storage (HTS). The machine that was used for the ball pull test is Dage 4000 series. A design of experiment (DOE) based approach is used to study and understand ball pull strength data based on effect of Ni thickness. Statistical results performed shows that 4um is the most preferred thickness for the Ni layer, thus giving a significant effect, supported by thinner Intermetallic layer thickness and area. © 2007 IEEE.