ESD Systems - Questions And Answers

If a tech. in the field had nothing else with him or her, would touching a grounded machine first, do any good at all before the tech handled the board. I say that it would, I am not saying that it would take the place of anything else that the tech should have. But this would reduce the chance of damage to the board. Touch the frame of the machine that is grounded to a proper wall outlet. I would say that this is better than nothing at all..would you not say the same thing? Nothing takes the place of the proper equipment, but......Should this not be done if you have nothing??? Another tech says this will do nothing at all, I do not agree...I think that it is better than nothing....and it will discharge into the machine to the ground.....this of course would be done before you handle the board in the machine or in the static bag.....can ya back me up?? - Chuck Neumann, Corinth, TX

Good question. Touching a metal chassis whether grounded or not will temporarily bring you to the same potential as the chassis. As soon as you let go though, due to charge induction and/or tribocharging from your clothes, from the contact area you make with the floor, a chair, etc., your potential will change from the chassis….sometimes almost immediately. You may have reduced the stored charge on yourself to a safe level, but there is no guarantee, in fact, most likely you will damage a device if handled without proper grounding considerations. This is a common misconception by a lot of field people, that touching ground will make you safe….it will only while you are touching ground….once you disengage that connection, you put all sensitive ESD devices at risk. Try this using a field meter…..look at the electric field that you measure on yourself after releasing the ground connection.

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