How to cure diluted PDMS with solvent

Hi,
I am doing some work with adding on a thin layer of PDMS that is diluted with a
solvent (DCM, THF, 1,4-Dioxane) on a silicon wafer by spin-coating or drop
coating. My problem is that I have noticed that I have bubbles on the backside
of the layer and I am having problem with curing it without getting bubbles. It
is either cavities of the solvent getting evaporated during curing or bubbles as
I might have to high temperature?
I usually cure at 100 deg. but I have also tried curing at boiling temperature
of the solvent and then later at 100 deg.
I usually have the ratio of 1:10 or 1:15 of the agent:elastomer. I add 1:6 ratio
of the PDMS:solvent. DCM has boiling point of 40 deg. and THF has a boiling
point of around 66 deg.
I am not sure what to do?
I need a thin (few micrometer) nice homogeneous layer (without cavities or
bubbles) that is molded into my structures of the wafer. My structures are in
the size of micrometers in size.
Reply to
thestargaze
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