A printhead module assembly includes a printhead integrated circuit (IC) assembly having a plurality of ink ejection nozzles arranged to form staggered rows, and defining a plurality of ink channels for supplying ink to the ink ejection nozzles; a flexible printed circuit board (PCB) electrically connected to supply both power and data to the IC assembly; a support sheet defining a plurality of ink holes and to which the IC assembly is bonded so that the ink channels are aligned with the ink holes; and a channel layer mounted to the support sheet adjacent to the IC assembly, the channel layer defining a plurality of slots aligned with respective air holes defined in the support sheet.