Patent ID: 7571525

Claim:
A method of manufacturing a liquid-jet head, comprising the steps of: forming piezoelectric elements, each of which includes a lower electrode, a piezoelectric layer and an upper electrode, on a side of a passage-forming substrate with a vibration plate between the group of the piezoelectric elements and the passage-forming substrate, in which passage-forming substrate liquid passages including pressure generating chambers and a communicating portion are formed, the pressure generating chambers communicating respectively with nozzle orifices from which to eject a liquid, and the communicating portion communicating with the pressure-generating chambers; and forming a penetrating portion by removing an area in the vibration plate which serves as the communicating portion; forming lead electrodes drawn out respectively from the piezoelectric elements, and sealing up the penetrating portion with an interconnect layer which is separated from the lead electrodes; joining a reservoir forming plate, in which a reservoir portion is formed, to the side of the passage-forming substrate, the reservoir portion communicating with the communicating portion, and constituting a part of a reservoir; forming liquid passages by wet-etching the passage-forming substrate from the other side thereof until the vibration plate and the interconnect layer are exposed; forming a protection film, which is made of a material having resistance to a liquid, on an inner surface of each of the liquid passages formed in the passage-forming substrate; detaching and removing the protection film on the interconnect layer; and removing part of the interconnect layer by wet-etching the part of the interconnect layer from a side at which the communicating portion is located, and thereby causing the reservoir portion and the communicating portion to communicate with each other, wherein, while the passage-forming substrate is being formed, the communicating portion is formed in a way that an edge of an opening of the communicating portion, which opening is close to the vibration plate is located outside an edge of an opening of the penetrating portion, and thereby at least the edge of the opening of the penetrating portion, which opening is close to the passage-forming substrate, is configured of only one of the vibration plate and the interconnect layer.