This paper demonstrates the characteristic of a thin sheet membrane for a mechanical driven micropump system by using a spin coater technique. The moving diaphragm for the micropump system was made from a PDMS polymer material. A plastic lidded dish with a diameter of 100 mm and height of 15 mm was used as a mould for this study. There were three variables that influence the membrane thickness formation during the spin coating process, which are the polymer weight, spin speed and the spinning time. It was observed that the final parameters to fabricate a thin sheet membrane are 2.5 g of PDMS polymer weight, 500 rpm of spinning speed and 180 s of spin time to yield a 314.82 ± 3.6556 µm thin membrane. This characteristic study is foresee could serve as a design guideline to fabricate a thin sheet membrane for a mechanical driven micropump system by using a petri dish as an alternative to a silicon wafer.