Patent ID: 8579418

Claim:
A method of manufacturing a liquid ejection head, comprising a multi-layer wiring substrate which has a recess-shaped structure and is provided with first electrical wires and first holes, and a liquid ejection substrate which includes piezoelectric elements and is provided with second electrical wires and second holes, the recess-shaped structure including a base section to form one of a ceiling and a floor of a common liquid chamber in the liquid ejection head and a projecting section to form a side wall of the common liquid chamber, the first electrical wires being formed at least partially inside the multi-layer wiring substrate, the first electrical wires being arranged inside the projection section along the side wall of the common liquid chamber, the method including the steps of: mechanically bonding the multi-layer wiring substrate to the liquid ejection substrate so that the first holes of the multi-layer wiring substrate are superimposed onto the second holes of the liquid ejection substrate so as to form electrical connections holes constituted by the first holes and the second holes; and filling a conductive paste into the electrical connection holes so that the first electrical wires and the second electrical wires are electrically connected via the conductive paste, wherein; the electrical connection holes do not have a uniform volume; and the first electrical wires provided with the multi-layer wiring substrate and the second electrical wires provided with the liquid ejection substrate are electrically connected through the steps of: filling the conductive paste into the electrical connection holes formed by mechanically bonding the multi-layer wiring substrate to the liquid ejection substrate; putting the multi-layer wiring substrate and the liquid ejection substrate which are mechanically bonded, into a vacuum chamber; reducing pressure inside the vacuum chamber; and returning the pressure inside the vacuum chamber to atmospheric pressure, after reducing pressure inside the vacuum chamber.