Patent ID: 7670757

Claim:
A method of producing an ink jet head including: a discharge port for discharging ink; an ink flow path which is in communication with the discharge port and has therein an energy generating element for discharging the ink; a substrate on which the energy generating element is formed; and an ink flow path forming member which is provided the substrate to form the ink flow path, the method comprising: (1) a step of forming a first layer of the photosensitive resin composition comprising an acrylic resin having at least one kind of structural unit represented by formulas 1 and 2 wherein in the general formulae 1 and 2, R 1 to R 4 each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms and a compound that generates an acid when irradiated with light on the substrate; (2) a first exposing step of exposing a part except a part serving as a first ink flow path pattern of the first layer up to a first depth in a thickness direction, wherein a reaction for making the exposed part of the first layer positive is at least a hydrolytic reaction of a carboxylic anhydride in the acrylic resin; (3) a first removing step of removing the exposed part of the first layer; (4) a second exposing step of exposing an outside of a part of the first ink flow path pattern in the first layer from a position of the first depth to the substrate, wherein a reaction for making exposed part of the first layer positive in the second exposing step is at least a main chain decomposition reaction of the acrylic resin; (5) a second removing step of removing exposed part of the first layer in the second exposing step to form the second ink flow path pattern in the first layer to form the first ink flow path pattern; (6) a step of providing on the first layer with the first and second ink flow path pattern, a second layer for forming an ink flow path wall; (7) a step of forming, in the second layer, an ink discharge port; and (8) a step of removing the first layer with the first and second ink flow path pattern to form the flow path.