A printhead assembly for a printer comprises a support member having a silicon core mounted within a metal channel; a plurality of printhead modules mounted on the support member, each printhead module including an integrated circuit manufactured using micro-electromechanical Systems (MEMS) techniques; and an elastomeric layer positioned between the core and the metal channel. The printhead modules and support members are configured to move into alignment with each other upon heating of the printhead assembly, and each printhead module is mounted to the silicon core with a neck portion.