Most electronic components are ESD.
Handle customer boards correctly.
If the device is labeled ESD handling you must use ESD handling (don’t say you are smarter than ESD)
Check you ESD ground Strap.
Most companies have a ground strap tester(you connect your ESD strap and insert the plug into a jack on the ESD tester, then press on the ESD tester will indicate pass or fail via sound or led.
If you are given a UUT or Customer board/component in an ESD enclosure,Treat it as ESD always-when inserting into a non power connector or removing from a non power connector.)
Mosfet component have been damage from improper ESD handling.
Worst is a latent failure(in which is component was damages but not yet evident.) This component has a greater chance of failure during use.
Sometime the ESD strap is connected to a ground jack on the test station (just remember if the ground is on your ITA(removable fixture) and its removed you may have broken the ground path).
Its better to be safe then to lose a customer supplied board because due to ESD which delays completion of your project because you can not complete integration.
Once a board is properly connected to it connector which has a proper ground connection and the device is powered you should NOT be using the ESD strap on that board.
Some companies/customers required a log of ESD Strap testing performed (daily,twice daily etc) to verify that the strap is making good ESD contact to your skin.
If you see a mat on a workstation Dont assume it is an “ESD mat” until it is checked out.
If you know you are going to remove an ESD board get ready with your ESD strap and a sealable ESD bag/container.
Verify with your Quality department on any new development on ESD handling and precautions.
Follow your companies procedure and ask before handling.
Test Engineers Resource 