Fowler Associates Labs

Response from the ESD Journal Expert

In response to the question ESD Journal reader Lorrie posed regarding static sensitive boards carried on type II or II bags Steve Fowler, Fowler Associates, resident expert for the ESD Journal, writes:

The question does not have an exact answer. 

It depends on
1. The sensitivity of the components on the board
2. The layout of the board (how are fields coupled to it)
3. Is the person carrying the board wearing ESD shoes or heel grounders and walking on protected or unprotected floors?

What Happens?
1.If there no high static fields present, nothing happens.
2. If there are high static fields present, the board will absorb the discharge of any touching or setting down during its presence in the field. If the board is charged, it will discharge more abruptly to a metal-out Type III bag than a metal-in Type III bag.  The Type II bag will always discharge the board more safely than a metalized bag. However a metallized bag in which the board is carried will always protect it more than a Type II bag if the static field is in motion.
Like I said, this is a very complex issue. 

The best answer is:
"why carry a board on a bag?"