Dear riyaz, As I also are working with SU-8 in the thickness range of 10 upto 200µm, I'm very interested in the paper of exposure optimzation. Thanks in advance. Regards, Peter Kuijpers Philips Applied Technologies/ EP&TF --- original message --- Hai, The pictures obviously show that it has been overexposed. I would suggest 30sec is more than enough for 20um... Make sure you are using Filter to remove lower wavelength's, because at lower wavelength's, SU 8 will obsorb UV light and its gives some unexpected results. If you want a paper regarding exposure optimzation, mail me I will send you as Attachment. Regards, Riyaz Pasha Shaik