I have a 4-layer board with no parts on the bottom side, the bottom-side solder mask fully covers all vias.
I want to stick the board with a double-side adhesive foil on the metal bottom side of a display. As I do not want to use the isolating double-side adhesive foil to cover the complete display area (you'll never would be able to separate the display from the PCB anymore in this case), I only use some stripes for sticking the PCB onto the display.
As the solder mask is not very thick I'm afraid of short circuits between the traces / vias of the PCB with the metal frame of the display.
So I would like to have something like an isolation foil (no high voltage isolation, only max. 30V) on the PCB's backside without having high costs and work. As far as know on flex-prints an isolation called coverlay can be used - could this be used for a rigid PCB as well? If yes: is this expensive? Or do you have any idea how to solve this isolation issue?