As chiplet packaging proliferates, a reduction in die interconnect pitch and concomitant increase in escape routing density must be enabled to meet performance and cost targets.  The traditional 2D solution (die on organic substrate) has limitations related to pitch and escape routing capability, which have promoted a shift to 2.5D technology (die + high density routing interface + organic substrate) in certain application spaces. Conventional thought is that use of a 2.5D solution can enable coarser, lower cost substrate design rules.  However, a different cost point for 2D vs. 2.5D means that interconnect and escape routing should be properly balanced between the organic substrate and the high-density routing interface, to contain cost while delivering the proper level of chiplet integration.  As both 2D and 2.5D solutions include an organic substrate, continuous development of higher routing density organic substrates is a prudent approach to enable cost-optimized solutions moving forward. This talk will cover current application space and limitations for 2D vs. 2.5D technology, and potential paths forward to achieve a cost-optimized,  complementary solution.