Some customers may come across the problems that they can’t assemble the dome array on PCB firmly. I think this may be caused by the followings:
First, there are some dust and stains on the PCB, so the PCB must be clear;
Second, the forceps or other toolings should be used to peel off the protective film of dome array, please don’t use the hand directly;
Third, please press slightly after you stick it on the PCB.
Via the above three steps, I think the dome array will be firmly assembled on your PCB.