[labnetwork] PDMS mold process?

[Russ Renzas]

This is extremely helpful Eric, thank you.

Thank you everyone on Labnetwork - I got about a dozen helpful responses, including many SOPs.

I'll take all this information back and work with the researchers.

- Russ
________________________________
From: Eric Johnston <ericdj at seas.upenn.edu>
Sent: Thursday, September 4, 2025 11:59 AM
To: Russ Renzas <rrenzas at unr.edu>
Cc: Lab Network (labnetwork at mtl.mit.edu) <labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] PDMS mold process?


[EXTERNAL EMAIL]

Hi Russ

We have a separate room in our cleanroom dedicated to PDMS mixing and molding. We have gloves of a very different color in that room which are required to be worn when working with PDMS and are required to be removed before exiting the room. Only the fully cured devices, cut out and with inlet/outlet ports already punched out, may be removed from the room. That said, most researchers use PDMS in their own (non-cleanroom) labs with very satisfactory results.

Regarding "gotchas", including tips and tricks, here are a few:
- Be sure to mix the two components VERY well, like for 5ish minutes. If they are not mixed well, the cured PDMS may stick to the master.
- An aluminum tray that can accommodate a wafer is very helpful. We got ours from Kitchendance.com, item #80063, which is big enough for a 4" wafer.
- A 1mm biopsy punch is a great way to add inlet/outlet ports.
- The main cause of failure of the master, next to delamination, is cracking of the wafer.
- It is easier to cut out only the devices needed. Trying to remove the wafer from the PDMS mold can easily crack the wafer.
- "Silanizing" the master can make it easier to remove the mold. We use Trichloro(1H, 1H, 2H, 2H-perfluoro-octyl) silane in a vacuum desiccator. This is really only necessary if there are small features with high aspect ratios.
- A drop of IPA when removing the PDMS mold can be very helpful. It acts as a lubricant.

Regards

Eric

Eric Johnston
Director, Quattrone Nanofabrication Facility
Singh Center for Nanotechnology
University of Pennsylvania
3205 Walnut Street, #109A
ericdj at seas.upenn.edu<mailto:ericdj at seas.upenn.edu>
T. 215.573.6695<tel:215.573.6695>
Questions? See the QNF FAQ<https://wiki.nano.upenn.edu/wiki/index.php?title=Frequently_Asked_Questions#How_do_I_get_started.3F>.

On Thu, Sep 4, 2025 at 8:08 AM Russ Renzas <rrenzas at unr.edu<mailto:rrenzas at unr.edu>> wrote:
Is anyone familiar with PDMS (or other material) mold fabrication? Any procedures or gotchas to worry about?

Bio faculty member asking if we can make molds in our fab. I only know how to make semiconductor, photonic, and quantum devices.

Thanks!

Russ

Russ Renzas
University of Nevada, Reno
_______________________________________________
labnetwork mailing list
labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
https://urldefense.com/v3/__https://mtl.mit.edu/mailman/listinfo.cgi/labnetwork__;!!IBzWLUs!QBwVjjk3FnBJge1V1iVK2eI93fYFZX5W8HHsErKejAMIgIM6vPEbkOBJE9_Q-3UQBJCFSmuYreoexXXboVE$

This email originated outside of the University of Nevada, Reno. Do not click on links or attachments unless you recognize the sender and know the content is safe. Report suspicious emails to the Office of Information Technology (OIT) at abuse at unr.edu.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mtl.mit.edu/pipermail/labnetwork/attachments/20250908/745135bb/attachment.html>