Low power and short time plasma treatment is a key because you want to
oxidize Si-CH3 group to Si-OH group, which binds to glass to form Si-O-Si by
losing water. If you treat the PDMS too much, Si-OH group on the PDMS will
condense with each other to form a SiO2 like structure.
After plasma treatment, you should put PDMS and glass together as soon as
possible because small molecular weight PDMS oligomer inside PDMS may come
out and contamminate the surface.
The reason to heating PDMS and glass is to remove water and drive the
condensation reaction.


On 11/9/06, Gareth Jenkins  wrote:
>
> The heat treatment makes a huge difference. After plasma treatment I use
> a hotplate at 85C for an hour or so and it works every time (I don't
> even bother cleaning the glass any more). Without it I only ever get
> very patchy bonding at best.
> For glass to glass you may also consider techniques involving dilute HF
> and pressure. I have never this but believe surface roughness is crucial.
>
>