What is the effect of humidity in ESD control circuit assembly and test environments?
High relative humidity (Rh) causes moisture to deposit and be absorbed by some materials. It does not eliminate triboelectric charge generation. Rather, it lubricates surfaces to reduce charge generation to some degree, and helps render material surfaces slightly more dissipative. The end result is lower charge generation and a lower residual charge. Unfortunately, Rh does not reduce charge sufficiently on ordinary materials to protect many ESD sensitive devices in critical assembly or laboratory areas. Never design your ESD control based on available humidity.
Rather, design your ESD control program assuming a low humidity (or no humidity) environment. The if Rh is available, it helps make a good program more effective. Like a special sauce heightens the flavor of well-prepared dish.
Finally, relative humidity and moisture will not eliminate charge. If it did, you would never see lightening during a thunderstorm.
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