Charged bare boards can attract contaminates from the air for one thing.
The foremost concern is assembling Electrostatically sensitive components
onto a charged bare board.  The newer designs are using components with a
sensitivity down to 5 volts in some cases.  There are people in the industry
who have started to consider a static charge on a pwb as a contaminate.

Al Cash

-----Original Message-----
From: Brian Ellis [mailto:[log in to unmask]]
Sent: Monday, February 28, 2000 3:15 AM
To: [log in to unmask]
Subject: Re: [TN] Stencil wear...NOT the metal one!


Daan

ESD? On bare boards? So what?

Brian

"d. terstegge" wrote:

> >From one of my stencil vendors I heard that ESD is a much greater concern
when using polyimide stencils. For that reason he doesn't sell them anymore,
in spite of the advantages of polyimide.
>
> Bye,
>
> Daan Terstegge
> Unclassified mail
> Personal website: http://surf.to/smtinfo
>
> >>> Murugan Vasudevan <[log in to unmask]> 02/27 8:29 pm >>>
> Hi technetters..
> here's an early bird question for this week...this one
> is regarding stencil wear. well, i have read in some
> literature that a fully hard laser-etched stainless
> steel stencil can last for more than a 100K cycles
> without ay problem. Now, the problem is, we are
> getting into this business of using a polyimide
> stencil. it is giving great deposits, good release
> characteristics, outperforms the metal stencil for our
> application, etc. etc. BUT...the one thing that
> concerns most of us is .."well, everything is okay
> NOW...but what might happen lets say 50K cycles
> after!?"..and i was wondering if anyone in this group
> has any experience with using such a stencil?" if so,
> i would definitely be interested in knowing how is it
> behaving on a long term basis..
>
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