a one - step process bonds a manifold to a printhead die and interconnection board located on a heat sinking substrate , encapsulates wire bonds extending from the interconnection board and the printhead die , and seals air gaps between the manifold and printhead die . a through hole is made in the heat sink substrate and communicates with a cavity defined by the manifold . during assembly , the manifold is positioned on top of the substrate containing the printhead die and the interconnection board and retained by pins . an encapsulation fluid is injected from an underside of the substrate through the through hole and into the cavity . injection is stopped when the fluid flows nearly to the front of the printhead . the process provides encapsulation of wire bonds , sealing of any air gap between the manifold and the printhead along a front face , and enhances structural bonding of the manifold to printhead components .