In Interposer type of designs, While each die is taped out in a 2.5D IC using a qualified PDK, how do you ensure the entire assembly is properly aligned and connected (die to die & die to interposer)? Design houses create custom flows, but these flows are not qualified by the foundry/OSAT and are not fully automated or integrated. We introduce a tool/cockpit that uses one design-independent assembly rule file and one results database to automate assembly creation and DRC and LVS checking, and verify complete interposer connectivity in-context. We demonstrate its successful use on a 2.5D interposer tape-out.