LED signs and large LED video panels are always subjected to harsh environment resulting to corrosion to their pcb mountings, here’s an app note from OSRAM about potting these LED panels for protection. Link here (PDF)
This note provides basic information about the potting of flat SMT LEDs in video wall and signage applications. Thereby details on material in use, examples of suitable equipment and the process are presented and described. Additionally, the note gives a short intro into video walls with a typical setup, varying LED type system effects and general challenges. Finally, the results of selected environmental tests are presented, to demonstrate their impact and the aptitude of potting protection method.