john wrote:
Interesting. What package types were susceptible to this (or did it
matter)? Metal can TO-x ICs seemed to be the most reliable (RTL, HLL,
some DTL, etc.) but I found a lot of early ceramic packages suffered
from bad seals and permitted fungi to enter and grow inside (this
in equipment that had never been wet, just from operating
environmental conditions). These parts seemed also to lack proper
passivation internally.
Air is also capable of introducing an ESD event. The tribo-electric
effect.
Air is an insulator. Drag molecules of it across an isolated device
(read blow), be it conductor or otherwise, and it WILL gain charge. Touch
to ground, and there is a discharge.
Nearly every "air station" one will find in a proper electronics
manufacturing facility will be at an ESD, properly grounded workstation
so that such discharges only occur at a slow rate. The "air tool"
operator is also supposed to remain grounded through a properly
constructed ESD grounding system. Either heal straps on an ESD matting
or floor set-up, or wrist or smock strap versions.
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