I have taken a F2 focusing screen apart to clean, the only clear film I encounted was a thin strip of sticky clear tape bound around the edges. This may have been to keep the two halves together or to keep dust out from between the two halves or both, I do not really know. However I did reasemble it, once cleened, without the tape and thus far ir has been fine but it is only 18 months since I clened it so not much time has passed and I have only put a dozen or so films through the camera since the clean.
Regards...W