Personally, I've found that the thick stuff is really tough to handle
so I try to go for the lower viscosity option whenever possible. 2075
is going to be a little (but not much) easier to handle than 2100, but
both are going to be pretty nonuniform right after being spun. So when
I make structures over 50 um I usually spin the resist and then leave
the wafer on a flat surface overnight to level out (possibly with a
cover over it depending on the cleanliness of the room). Then the next
day I bake and process the wafer. I keep the resist in the bottle it
came in, and pour right from the bottle. You can store it in a fridge
if you like, but a cool, dark, dry place is fine. If you do store it
in a fridge then you have to be sure to take the bottle out a day
early and let it warm up to room temp before you open it or else
moisture can condense in the cold bottle when you open it.

good luck
Joe Grogan



Quoting Sheng Zhang :

> Hi, all,
>
> I need to decide which SU-8 to purchase, 2075 or 2100. I will use SU-8 to
> build a 150um~200um structure.
>
> The datasheets suggests both of them can achieve ~ 200um thickness. The
> difference is spin speed - higher for 2010 because of its higher viscosity.
>
> I think using higher spin speed would result in better thickness uniformity,
> but I'm afraid with relative higher viscosity 2010 might be harder to handle
> (especially when dropping/pouring out of bottle)...
>
> Another question: where do you keep the resist? Get some in a small bottle
> or just keep them in the original bottle?
>
> And under what temperature? My cleanroom keeps all the photoresist in a
> fridge..I think that would make 2075/2010 even harder to handle when they
> are cold...
>
> Any suggestion?
>
> Thanks!
> Sheng

--
Joseph Grogan
Graduate Student
Department of Mechanical Engineering & Applied Mechanics
University of Pennsylvania
220 South 33rd st
Room 229, Towne Building
Philadelphia PA, 19104
Lab Phone: 215-898-1380