Can Mounted Parts Still be Damaged by ESD?

Guest

Is it true that parts already mounted on a board can still be damaged by ESD? I thought parts in a circuit are already safe from ESD? This is what my sup told me a couple of years ago.

Secret

Guest

its usual misconception that mounted parts are protected from esd because the pins are no longer floating. however if you think about it you can still deliver a pulse directly to a pin of a mounted device so you can still destroy it by hbm or mm. i’ve also read pcb's or assemblies can store a lot of energy because of its high capacitance. this stored charge may be released as esd if a metal trace of the board touches a grounded surface. ic’s connected to the shorted trace will be destroyed. they call this charged board model or CBM esd.

rel eng