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<p>Hi Julia!</p>
<p>Great catching up with you at UGIM! <br>
</p>
<p>Just a few, quite possibly unrelated, comments about PDMS (which
is one of my favorite materials...) Most people use Sylgard 184.
This is what is used in most literature references and it is handy
because it self-cures. At SNF, we recommend using Sylgard 182
because this does not self-cure (well, actually it eventually
does, if you leave it long enough.) There are several advantages:</p>
<p>1. Spin coating. Because it self-cures, the viscosity of 184 is
said to double about every hour or so (to my recollection.) The
non-self-curing 182 allows for a more consistent/longer working
time, if thickness control is an issue for your experiment.<br>
</p>
<p>2. Even if you bake Sylgard 184 for the recommended time, it
will continue curing. For researchers who are doing microcontact
printing or have other applications where small changes in
elasticity, surface energy, etc. will matter, this could be very
important. I haven't experienced this myself, but was told by one
of our research groups that their experimental results experienced
a drift over the course of a month when they used 184, but that
they had day-to-day consistency when using 182. <br>
</p>
<p>3. The Sylgard 182 components come in jars. I can use
disposable syringes to extract and meter out exactly what I want,
whereas the last time I purchased Sylgard 184, it came in a wacky,
dual-syringe dispenser.</p>
<p>One other caveat about the Sylgard products: these are potting
agents, not precision-engineered materials. There's a lot of
batch to batch variability and limited shelf life -- and the main
issue is variability in curing. Even really old, out of date
stuff will work great if all you want to do is to cast a
structure. But researchers requiring a higher degree of
consistency should be aware that they will need to control for or
account for this variability.</p>
<p>But getting back to your question about PDMS... Whether 182 or
184 is used, it would be best to make sure it is thoroughly
baked/cured before metal deposition. It would also be good to
make sure your researchers use fresh/non-expired material, or bake
the living heck out of it if it is expired (though at $80/kg,
there should be almost no excuse for keeping old stuff). Both 182
an 184 also have a high thermal expansion coefficient, so keeping
deposition temperatures low is important to prevent buckling of
the films.<br>
</p>
<p>Mary</p>
<p><br>
<span class="moz-txt-tag">-- <br>
</span>Mary X. Tang, Ph.D.
<br>
Stanford Nanofabrication Facility
<br>
Paul G. Allen Bldg 141, Mail Code 4070
<br>
Stanford, CA 94305
<br>
(650)723-9980
<br>
<a class="moz-txt-link-abbreviated"
href="mailto:mtang@stanford.edu">mtang@stanford.edu</a>
<br>
<a class="moz-txt-link-freetext" href="http://snf.stanford.edu">http://snf.stanford.edu</a>
<br>
</p>
<p><br>
</p>
<br>
<div class="moz-cite-prefix">On 6/17/2016 3:21 PM,
<a class="moz-txt-link-abbreviated" href="mailto:julia.aebersold@louisville.edu">julia.aebersold@louisville.edu</a> wrote:<br>
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<div style="direction: ltr;font-family: Tahoma;color:
#000000;font-size: 10pt;">Greetings everyone! I had a great
time at UGIM and enjoyed seeing old friends and making new
acquaintances. The University of Utah hospitality was
fantastic. I do have some questions.
<div><br>
</div>
<div>1. We have had an aluminum adhesion issue with bubbling
under the deposited film. We have had a user put their PDMS
devices into our sputtering tool and have been told that
outgasing PDMS could be the source of our bubbling underneath
aluminum. We do not see this behavior with other metal
depositions. Do you ban PDMS from your processing chambers?
Also, we will go ahead with decontamination using sand
blasting and solvent wipe downs, but do you recommend other
processes (i.e. chemical dips for parts that can be removed)?</div>
<div><br>
</div>
<div>2. My second question revolves around organizational
structure. We currently have a Faculty Director, Cleanroom
Manager (me), 3 Engineers and 1 Admin. Structures and the
number of people in facilties vary immensely due to size of
the facility, but I wanted to know how many split their
cleanroom manager position into a technical manager and
business operations manager. The business operations manager
would primarily handle administrative tasks and rarely step
foot into the cleanroom.<br>
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<p>Cheers!</p>
<p><br>
</p>
<p>Julia Aebersold, Ph.D.</p>
<p>MNTC Cleanroom Manager</p>
<p>University of Louisville</p>
<p>2210 South Brook Street</p>
<p>Shumaker Research Building, Room 233</p>
<p>Louisville, KY 40292</p>
<p> </p>
<p>(502) 852-1572</p>
<p><a moz-do-not-send="true" tabindex="0"
href="http://louisville.edu/micronano">http://louisville.edu/micronano/</a></p>
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