Homebrew PCBs

My last word on the subject.  My examples were obviously fabricated to try
and demonstrate that just because you don't see a problem immediately
doesn't mean there isn't one and the results could be a disaster.
Suggesting a plastic shield for my mill example shows you've deliberately
missed the point.

Your own examples are typically anecdotal without any evidence other than
it's never happened to me or anyone I know so it must be alright.

I've seen micro-photographs of ic's that have been opened up after
exposure to static electricity and not just the door snapping carpet
generated kind.  The devices are clearly damaged.  It's true they are
better than the late 70's but it's still important to take precautions.

The companies recommending using reasonable anti-static procedures are not
just the companies who sell the anti-static materials but all companies
who have an interest in seeing parts and products function correctly.
Fortunately for us they determine what works and what doesn't so that we
don't have to suffer the consequences.

For each example I'm sure you'll have another 'story' of how we don't need
to worry. I've said enough about it since arguing the religion of "no anti
static handling needed" based on "it's never happened to me" is rather
pointless.

John Dammeyer

Automation Artisans Inc.
http://www.autoartisans.com/ELS/
Ph. 1 250 544 4950


-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Stefan Trethan
Sent: Saturday, December 24, 2011 3:16 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] PCB holder




There are about a gazillion reasons why the milling machine controller
might go haywire, such as a bad solder joint or because someone forgot
a decoupling capacitor. In my opinion the chance for that to be caused
by ESD damage is so small, I rather put the effort into building a
lexan enclosure that will catch the flying tool bits or invest the
money in personal protection equipment for mechanical hazards.

I understand why you would want to be fastidious about ESD damage in a
semiconductor plant, you don't know where the parts will end up and
must meet the quality requirements of all customers. But you don't
need six-sigma quality if you make some circuit at home or even
commercial prototypes. The other error factors such as improper
soldering, faulty design, etc. will far outweigh any chance of ESD
damage. Don't confuse the quality standards of industrial mass
production with someone soldering something together on his bench.

I understand that ESD damage may not show any immediate signs, but
even the cases where semiconductors have failed "for no apparent
reason" are exceedingly rare. There just aren't any significant number
of parts failing, so there is no possible payback for any measures
taken.

Now, any more examples of even suspected ESD damage anyone? Again, no
production line stories please! Home shop or development lab only, I
do not want to argue about one-in-a-million events.

ST

On Sat, Dec 24, 2011 at 10:39 AM, John Dammeyer <johnd@...
<mailto:johnd%40autoartisans.com> > wrote:

> Not everyone who builds PCBs at home builds frivolous projects that do
no
> harm when they fail.  A failed milling machine controller that has the
> table move erratically destroys a tool bit snapping it off and flinging
it
> across the room or into someone is always a possibility,  even if small.
>






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