Thomas,

Thanks again.  One tip that may be helpful for you:  If you are using
a basic lab hot plate, by putting a block of aluminum that is about
1/2 inch thick on top you can buffer the temperature variations quite
a bit.  It takes a bit longer to heat it up, but the variation is
reduced substantially and results may be more consistent.

Brad Cantos
brad.cantos@holage.com
http://holage.com

On Aug 22, 2009, at 5:43 AM, Wilson, Thomas wrote:

> Brad,
>
> Here's more info on doing lift-off of sputtered metals with AZ5214E.
>
> Regarding my recipe for liftoff with AZ5214E for small numbers of
> samples, as the temperature on a hot plate varies substantially (not
> quantified yet myself although I'm looking into traceable IR
> thermometers to do so), for the post-bake I position only a single
> chip (12 mm x 16 mm) in the center of the 6" x 6" hotplate each time
> for consistency (probably out of the question for any serious
> production work). For the pre-bake (I don't find it to be as
> critical), I position 4 chips in a 2 x 2 array in sequence and
> remove in same sequence to ensure equal times on the hotplate.
> Perhaps this is the reason I've been getting consistent results. I
> forgot to mention, I use "AZ Developer 1:1" for 2 min 15 sec
> (contact Mays Chemicals in Indianapolis, IN ~$130 for 4, 1 gal
> containers), as it doesn't etch aluminum and I've found quite a
> number of other common developers do attack aluminum.
>
> Thomas