Graham,
ESD safe Velcro is available. The important thing to note is that it is silver in color. I assume due to some method of incorporating a dissipative or conductive material. It does cost much more than plain black Velcro. I don't have any sources off the top of my head but assure you what you want is available. The only alternative is to place and remove the black Velcro with a benchtop ionizer running and the airflow aimed to cover tray and strap as the work is done. A compromise but it would help lower the ESD threat.
Drew Meyer
Benchmark Electronic, Inc.
-----Original Message-----
From: Collins Graham [mailto:[log in to unmask]]
Sent: Friday, April 25, 2003 6:01 AM
To: [log in to unmask]
Subject: Re: [TN] Velcro straps for matrix trays?
Hi Eric, Brad, Arthur
Thanks for the replies.
Eric - An interesting observation, I've just blindly assumed that the
manufacturer of the components would supply them with an appropriate ESD
safe velcro strap. A dangerous assumption perhaps. But how dangerous
is it given that the tray is conductive, the bench is conductive, and
the operator putting on or removing the straps is grounded?
The problem I've got is that these QFPs are big, ceramic, and have
leads that behave as if they are made of butter. They have to be
received, inspected, tinned, inspected, and pick/placed - so a fair bit
of handling and examination. Using elastic bands has been a disaster,
although my abilities to tweak leads with ax X-Acto knife are improving
as a result. Using Kapton tape to secure the trays together has not
worked well either, it only takes marginal movement to allow the parts
to shift. The only success I've had is using the big clamp type paper
clips, one can fasten two trays together with a clip on each end and
there is no movement. Not a really practical solution though.
The velcro straps work wonderfully, but we only have a couple in house.
Most of our matrix tray packed parts arrive ready to use, with heat
sealed plastic bands holding them. These don't get opened until we are
ready to use them.
Thanks all, and have a good weekend.
Oh, and Peter Duncan - I flipped a long time ago. This is not new
news. Just trying to put a bit of humor into a forum that has gone a
bit dry...
- Graham Collins
regards,
Graham Collins
Process Engineer,
Northrop Grumman Canada Corporation
Halifax
(902) 873-2000 ext 6215
>>> [log in to unmask] 04/25/03 04:51AM >>>
Hi Graham,
Having been responsible for starting the recent discussion on
abbreviations, I will be careful how I answer this query.
We receive matrix trays with Velcro strips securing them. The strips
are black and give the appearance of being made of a conductive
material. But not so. I have measured 100kV static when removing the
strips quickly and 20kV when taking them off slowly. I prefer elastic
bands, they generate a little static but they are not in the same league
as the Velcro.
Regards
Eric Dawson
> -----Original Message-----
> From: Collins Graham [SMTP:[log in to unmask]]
> Sent: Thursday, April 24, 2003 5:58 PM
> To: [log in to unmask]
> Subject: [TN] velcro straps for matrix trays?
>
> Good day Technet!
> A politically correct, abbreviation free question today. Nah,
forget
> that! I don't have time to avoid acronyms.
>
> We have a problem with very expensive QFPs - they arrive on trays,
and
> at some point either internally, or externally when we send them out
for
> tinning, they are badly packaged. The matrix trays have in some
cases
> has been held together less than firmly - elastic bands, for
example.
>
> So - I'm looking for a source for velcro straps to put on matrix
trays.
> A mundane question for such a highly technical body, but hopefully
> someone can shoot me the one liner "buy 'em from..."
>
> On a less serious note, how do we know that Jason and Steve Gregory
are
> not the same person? Anyone ever seen them together? Maybe Jason
> Gregory is the good twin and Steve "Jaegermeister" Gregory is the
bad
> one??? The answers "it depends", "to quote St. Doug, 'it depends'",
or
> "they aren't the same, and we can't get broadband access for our
> commodore PET computers in Cypress" are not acceptable. If you run
a
> Steve Gregory through a Westek Triton V inline cleaner, Strap an
AutoSIR
> to him, and then check him in a Contaminometer, what results would
you
> find?
>
> Have a good day all. TTFN!
>
>
> regards,
>
> Graham Collins
> Process Engineer,
> Northrop Grumman Canada Corporation
> Halifax
> (902) 873-2000 ext 6215
>
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