1. Field of the Invention
The present invention relates to a method of manufacturing a liquid ejection head for ejecting a liquid.
2. Description of the Related Art
A typical example of the liquid ejection head for ejecting a liquid includes an inkjet recording head applied to an inkjet recording system ejecting ink to a recording medium for recording. The inkjet recording head generally includes an ink flow path, an ejection energy generating unit disposed in a part of the flow path, and a fine ink ejection port for ejecting ink by energy generated therein.
Japanese Patent Application Laid-Open No. 2006-168345 discloses a method for manufacturing a liquid ejection head applicable to the inkjet recording head. The method includes forming a flow path mold on a substrate having a plurality of ejection energy generating units; and applying thereto a covering resin layer made of a curable resin and for serving as a flow path wall member having a flow path wall. The method further includes curing a portion surrounding the mold serving as the flow path wall and containing an upper surface of the covering layer; laminating a polished silicon plate thereon; forming an ejection port in the plate; and then removing an uncured portion of the covering layer and the mold to form a space serving as the flow path.
In recent years, the recording apparatus has been needed to increase the image quality and the recording speed to higher levels. In order to meet the needs, the ejection ports and the flow path communicatively connected thereto are required to be arranged at high density and the volume of each droplet to be ejected is also required to be equalized at further higher levels.
Unfortunately, the method disclosed in Japanese Patent Application Laid-Open No. 2006-168345 has a possibility that the covering layer may have a slightly uneven upper surface thereon due to existence of a partially remaining flow path mold in the entire substrate surface. If the silicon plate is arranged so as to conform to the uneven surface, the distance between the ejection energy generating unit and the ejection port may vary. If that happens, it is concerned that the variation of the distance causes a variation of the volume of a droplet ejected from each ejection port, which may affect an image to be recorded. Even if a high pressure is applied to laminate the silicon plate to the covering layer, it is difficult to planarize the covering layer sufficiently enough to remove the unevenness thereof because the upper surface of the covering layer is partially cured.