US Patent 7270398 Circuit board and liquid discharging apparatus

A circuit board for a liquid discharging apparatus in which coating performance of a protective layer and a cavitation resistive film on a heat generating element is excellent and durability is excellent and a manufacturing method of such a circuit board are provided. A surface portion of a wiring material layer is processed so that an etching speed of the surface portion is made higher than that of the material forming the wiring material layer. It is desirable to execute a process for forming at least one selected from a fluoride, a chloride, and a nitride of the material forming the wiring material layer into the surface portion of the wiring material layer.