Aiming for X-ray astronomy applications, we prepared large-area submicrometer polyimide (PI) films [diameter (Φ) = 8 cm] with great thickness uniformity via the spin-coating technique by using a PI precursor, poly(amic acid) (PAA) derived from 3,3′,4,4′-biphenyltetracarboxylic dianhydride, and p-phenylenediamine as the starting materials. The effects of the spinning speed, apparent viscosity of the PAA solution (η), and spinning time on the PI film thickness and its uniformity, as characterized by the measurement of the film thickness every 0.5 cm along the diameter direction, were investigated. By optimizing the spin-coating conditions, we prepared final submicrometer PI films with average thicknesses in the range of 200–850 nm and with film thickness fluctuations of less than 1.3%. The pressure bulge test results indicate that at a thickness of 805 nm and an inside test aperture diameter of 2.64 cm, the prepared PI films reached a final burst pressure of 20.2 KPa; this suggested excellent mechanical performances in the self-standing submicrometer PI film. This study makes a contribution by providing a typical example and opening the way for the preparation of robust self-standing submicrometer PI films with great thickness uniformities for X-ray astronomy applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39977.