The datasheets provide charts of Exposure Energy (mJ.cm-2) vs. Film Thickness.

You can calculate the exposure time given that 1 W = 1 J.s-1

Just be aware that the UV power may not be uniform across the chuck.

Jules

I'm not really adding much to what Jules Lloyd Hammond said, but i'm saying it in a slightly different way. Just add "/S" to your power rating. If you want 204.4 mJ/cm2, you'll need to expose for 10 seconds. Use the exposure chart for the thicker resist.

Thanks guys for the answers, I finally understand how to calculate it this time!

You can see the previous work of Prof.Michael Breadmore which is published in Lab on a chip

Thanks Zaidon, I will read the paper.

Hello all,

I need help to know, how to find out or calculate the power ( in %) to feed in the UV-KUB 2 and time. If the thickness of the SU-8 2050 is 100um. -8 2050 is 100um.

Hello Shubha Jain ,

Kloe state that the UV-KUB 2 has a power density of 40 mW.cm-2 at a wavelength of 365 nm or 405 nm.

Your "dose" is usually associated with the exposure time. I would not know whether the results of this machine would be better with a higher power density and shorter exposure time or lower power density and longer exposure time. I would be tempted to adjust the power percentage such that the output power density was in line with other commercial machines. Say around 10-20 mW.cm-2, so between 25-50%.

https://www.kloe-france.com/en/laser-lithography/photolithography-systems/uv-exposure/uv-kub-2

When exposing >80 micron SU-8 with a contact mask, it's a good idea to keep the power on the low end. Too much power will cause some heating of the resist surface that can cause your mask to stick to the resist. This is usually very subtle with resist sticking to mask in barely noticeable places but the result is a dirty mask that produces rough edges.

Thank you so much Jules Lloyd Hammond and Ron Reiserer for your answers.

So how much power should I keep it? Around 10-20 mW.cm-2, so between 25-50% , so it will be around 24s-12s if exposure energy is 240mj/cm2 for 100um thinckness. Is it fine?

I typically use 10mJ/cm2. As a side note, I usually do a longer softbake than the data sheet suggests which gets rid of more of the solvent. Residual solvent acts as a photoinhibitor and lowers the Tg. If you have some residual solvent because of a short bake, 10mJ/cm2 may still soften the resist enough to get some transfer to the mask.