I am working for a startup company that makes microfluidic molds and I was wondering if Trichloro(1H,1H,2H,2H-perfluorooctyl)silane eventually wears off after a certain number of molds using PDMS? I was under the impression that it lasted forever but we are currently making over 50 molds a week on our wafers so I figured I would ask.
Over 50 uses is pretty good to be honest! I believe the way it works is when you deposit the silane on the Si wafer, you deposit a thin layer that is covalently bound to the wafer and all the layers that deposit on top of that are just loosely deposited. When you pour PDMS on it the PDMS is able to set and come-off easily since it is touching the loose silane layer and not the covalently bound layer. As you consume the loose layers by molding more and more PDMS you eventually reach the covalently bound layer and at this point the PDMS is able to permeate the layer and also form a stronger adhesion to the wafer surface. (This is my educated guess and not something I tested)
I recommend that you try increasing the deposition time of the silane to achieve higher thickness of that loose layer and perhaps that will give you increased number of PDMS molding cycles. Let me know if you try it! :)
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