The resistive layer of ZENITHSUN Thin Film Resistor is sputtered onto a ceramic base. This creates a uniform metallic film of around 0.1 um thick. Often an alloy of Nickel and Chromium (Nichrome) is used. Thin film resistors are produced with different layer thicknesses to accommodate a range of resistance values. The layer is dense and uniform, which makes it suitable to trim the resistance value by a subtractive process. Photo etching or laser trimming are used to create patterns in the film to increase the resistive path and to calibrate the resistance value. The base is alumina ceramic.