High-quality polyimide thin-film is fabricated by spin-coating

and the relationship between film thickness and rotation speed is studied. Electric breakdown test is carried out on the prepared thin-film with different thickness

and effects of the film thickness on electric breakdown property are studied. Results indicate that there is a linear positive correlation between the film thickness and reciprocal square root（ RSR） ω

-1/2

of rotation speed. By controlling rotation speed

different film thickness can be obtained

the thicker the film is

the higher the breakdown voltage

but lower average breakdown strength will be obtained. The maximum breakdown voltage and breakdown strength of the prepared polyimide thin film imidized at

280 ℃ are 2 370 V and286. 33 k V/mm

respectively. This means that the polyimide thin film fabricated by spin-coating can meet the insulation requirements of a wide variety of micro-electro-mechanical system（ MEMS） devices.