Introduction
Polymethylsiloxane (PDMS) is material that is optically clear, and generally considered to be inert, non-toxic and non-flammable. This document describes how to mix, degas and cast PDMS onto a mold that has been made by your favorite technique (UV lithography, Ebeam lithography...)
Associated documents and references
- How to process su-8 2015
- Soft-Lithography (what is soft-lithography)
David C. Duffy, J. Cooper McDonald, Olivier J. A. Schueller, and George M. Whitesides, “Rapid
Prototyping of Microfluidic Systems in Poly(dimethylsiloxane)” Anal. Chem. 70, 1998. pp. 4974-4984.
Equipment used and safety considerations
- desiccator
- scale
- weighting cup
Read PDMS MSDS before processing.
Recipe Parameters
PDMS comes in the form of 2 liquid components (component A: the base and component B: the curing agent) that are mixed to a ratio of 10:1 %w. After casting the PDMS on a mold and curing it it becomes solid and can be used for various applications.
- Prepare the work area with protective rags so spills won't go on the directly on the table
- Grab the 2 components that are located in the blue solvent cabinet of the yellow room
- Put the weighting cup on the scale and press TARE
- Pour the needed quantity of PDMS (max 30g). Beware of spills. Clean any spills right away with rag and acetone
- Press TARE again and pour component B, measure 1/10th of the weight of component A
- Mix the two component for 1 minute using a plastic swab
- Put the cup in the desiccator located underneath the table of the yellow room
- Leave under vacuum for 10min and bring back to atm pressure. Repeat step 8 until no bubble remains in the cup
- Place your mold in a closed container and pour the degassed PDMS on it. Degas again if needed. If the mold is made of silicon an anti-adhesion treatment is needed to ease the peeling of PDMS when cured. This can be done is the AMAT P5000 with the recipe CHF3 TREAT.
- Place the container in the oven @ 60-70°C for 4 hours or overnight to get it to cure
- Peel off the PDMS and cut it to your needs with a razor blade
PDMS can be cleaned with acetone and IPA. During cleaning PDMS will swallow the IPA and bend. After drying the bending will go away.
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