The packages used for this study are shown in Table I. It can be seen that there are many different sizes, pin-counts, lead-finishes and solder ball types for these packages. The more notable ones are: ceramic column grid array (CCGA), plastic ball grid array (PBGA), FLEXBGA, and SMC. The overall dimensions of the 1657CCGA are: 42.5 42.5 6.5 mm ³. The Sn-90(wt per cent)Pb solder columns are arranged in a 41 41 array at 1 mm pitch with six depopulated at each corner. The diameter of the solder columns is 0.5 mm and they are 2.21 mm tall (Lau et al., 2004a). The Sn-90Pb solder columns are joined to the ceramic substrate with Sn-Pb solder and joined to the PCB with either Sn-Ag-Cu or Sn-Pb solder. The pad size on the ceramic substrate is 0.8 mm and on the PCB is 0.673 mm. It should be noted that the CCGA package is not subject to the European lead-free regulations because its solder column content is more than 85 wt per cent of Pb. This is one of the exemptions given by the European Restriction of Hazardous Substances (RoHS) directive.