What kind of glue Apple uses on iPhone 3G* digitizer

i would like to know what kind of glue apple uses to keep the digitizer screen to the frame, i know uses 3M adhesive strips, but theres a thin line of blue/clear glue like silicon or epoxy that strength the digitizer.

so far, i been using:

3M adhesive strips= hold ok for a couple of days, but always get loose on the top right corner.

3M adhesive + super glue=BAD alot of mess

3M adhesive +Loctite GEL Control = OK, but not so much.

Do somebody know which glue Apple uses? it should be the same on the screen and chrome bezel to back housing.

i been searching alot on the forums and google, but could not find an answer.