IC Handling and Humidity

Thread Starter

Steve1992

Joined Apr 7, 2006
100
I always thought that the higher humidity is, the worse conditions for IC (in particular CMOS) handling, because of the moisture in the air.

But I read, the less moisture in the air the more friction insulators and human bodies can generate a static electric charge.
 

hgmjr

Joined Jan 28, 2005
9,029
I believe as a rule, static charges can build up to higher voltages as the humidity decreases. Correspondingly, static charges have a harder time building up to high levels when the humidity is high.

For example, you may have noticed that the incidents of static discharge between yourself and the body of an automobile increases when you step out onto the ground during the winter months when the humidity is low.
During the summer when humidity is higher such a discharge is rare.

hgmjr
 

John Luciani

Joined Apr 3, 2007
477
I always thought that the higher humidity is, the worse conditions for IC (in particular CMOS) handling, because of the moisture in the air.

But I read, the less moisture in the air the more friction insulators and human bodies can generate a static electric charge.
There is more than one failure mode.

The lower humidity decreases the risk of damage due to static electric charge.

The higher humidity can cause damage during the soldering process.
Moisture in the package will vaporize during soldering and can cause die
and package damage.

The moisture issues are worse for SMD packages which are thinner.
Lead-free soldering is done at higher temperatures which makes the problem even
worse.

(* jcl *)
 

techroomt

Joined May 19, 2004
198
electro static discharge is a concern when handling devices. esd does become worse as humidity lowers. matter of fact, esd handling should cease below 30% humidity, unless using an air ionizer (or similar device), and all stop work below 20%. all handling of sensitive devices should be done with grounding wrist straps and proper procedures and work surfaces.

interesting info john on assembly concerns, thanks.
 
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