bubble formation when glue-bonding with adhesive droplet

Dear reader,
when contacting a solid surface with a sessile liquid drop, a gas bubble
forms depending on viscosity and momentum of contact.
What´s the physicochemical reason?
Any literature?
My problem in detail:
I am trying to join two glass chips (several mm edge length) with a
liquid adhesive. For this I place one chip under a stereomicrosocope,
dispense a drop of adhesive (ca. 30 microL, visc. 4000 mPas, degassed,
UV-cure) onto it, grab the second chip with a tweezer, approach the
drop vertically from atop, make gentle contact and release the second
chip.
The drop initially is bubble-free, but in the moment of contact a gas
bubble forms with a diameter of about 0.1mm.
I tried 2K-silicone with the same viscosity: same result.
I tried Polycarbonate and Polystyrene as transparent chip materials
with the same outcome. I placed small droplets on both surfaces: same
result.
When using droplets of higher viscosity, the bubble diameter
increases.
I electrostatically discharged all materials.
Only reducing the approach velocity yields a bubble-free joint.
So, it´s not surface tension related (?)
What is it?
Thanx in advance,
Martin