What adhesive glue will work

If I'm not mistaken, cellphones do not use adhesive glue for screen or back covers. Precision injection molding plastic covers snap fit precisely into rear phones using mating tabs. If it were not for precision injection molds, covers would not fit perfectly. Most covers are snap fitted and pried carefully to unsnap them without damage. Screens are usually snap fitted to the front with double stick tape holding screens to the main body. Separating screens may require heating the front of the screen to soften the adhesive before separation can occur. Battery packs sometimes use double stick tape for retaining battery pack to main phone body.