As the vias were drilled to meet the EAC metal pad, the top layer pad had to be patterned to cover the via in the next buildup pattern process. As we used a larger via, a larger pad had to be designed that accommodated not only the required via size, but also thepad-to-via alignment accuracy,anyunderlying pad to-pad deviations, and any differences/uneven shrinkage at this ceramic area versus rest of the polymer core.Fig.6 summarizes the design considerations described above.