Homebrew PCBs

I was charged (so to speak) with finding the problem with automotive instrument clusters that were failing a test in a particular facility.  As long as the workers were wearing their static dissipative straps and non-static clothing, and following the proper discharge procedures fitting clusters to the fixtures, 100% of the products worked.  As soon as they slacked in any area, failures rose to about 20%, of which about 5% were permanently dead.  That was a lot of lost product.  Not too many years ago, either.  Three or four.

Donald.
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----- Original Message -----
> From: "Stefan Trethan" <stefan_trethan@...>
> To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
> Sent: Sunday, December 25, 2011 8:19:36 AM
> Subject: Re: [Homebrew_PCBs] Re: PCB holder
> People who say "because that's just how it is" or "end of discussion"
> as a rule are not worth my time talking to.
> 
> I can't find any good statistics on ESD damage. There was one
> reference to a comparative test that showed a reduction in production
> rejects of about 1%, but it comes as an example out of a book
> promoting ESD measures and there are no details about the type of
> circuit or handling. It's not an easy experiment to make - how do you
> create typical handling and how do you prove a part is damaged or not?
> Once you introduced ESD measures you create no more data -
> before/after comparisions are difficult since ESD measures are often
> accompanied with other improvements in handling, such as preventing
> mechanical damage.
> 
> I store all parts in (cheaper) non-esd safe containers (bins and
> drawers made from polystyrene or polypropylene) and have never found
> one that wouldn't work, that I could recall now. Same for the tools,
> they are slightly cheaper in the non-ESD version so I use those.
> Adding up the cost for ESD safe environment would easily run into
> several hundred $, so that doesn't seem cost effective to me.
> 
> Half way measures can be more dangerous than nothing, for example
> walking with regular shoes on ESD flooring builds much more charge
> than on regular flooring, but of course there are some effective
> measures that are also free, such as first touching the chassis or
> ground.
> 
> By the way, did you know they sell wireless ESD wrist straps now?
> <http://www.amazon.com/Cables-Unlimited-ACC-1410-Wireless-Static/dp/B000A1E6FY>
> Now make up your own opinion about _that_.
> 
> ST
> 
> 
> 
> On Sun, Dec 25, 2011 at 1:26 PM, Benjamin Blumer <b3nzilla@...>
> wrote:
> > It is compelling to have someone with credentials stand on one side
> > of the
> > fence. But I think it would be much more compelling, and more
> > satisfying,
> > to have said person explain their reasoning.
> >
> > Sent from my iPad
> >
> 
> 
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