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May 2007

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Subject:
From:
Wayne Thayer <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wayne Thayer <[log in to unmask]>
Date:
Mon, 7 May 2007 16:48:54 -0400
Content-Type:
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Samtec is kind of funny like that.  If someone asks them for a
connector, they put it into their catalog, seemingly without thought on
whether the part might really make sense.  They seem to think the
requestor understands their needs.  So I have a number of design
engineers who specify these things.  They even buy the parts before I
see the design and explain why they won't work.  The engineers always
respond with "If the connector can't be used reliably, why does Samtec
have it in their catalog?"  I have a couple 200 pin 4x50 SMT headers in
my office from Samtec which have about a 30 pound (13.6kg) extraction
force!

Wayne Thayer

>>> [log in to unmask] 5/7/2007 3:15:12 pm >>>
Hi Phil!

We don't make choices regarding SMT connectors, our customers do, and
I
can tell you I've seen a lot of different styles.

There's one thing about them that I've seen lately that I really don't
like, and it's mainly the SMT connectors that come from Samtec.
Lately,
they been coming out with some high-density fine pitch designs that
are
flash gold plated (RoHS compliant!), and that's the ONLY WAY you can
get
them now. Flash gold is the RoHS finish of choice it seems for Samtec.
But now to comply with the J-STD, you must remove gold no matter what
the thickness on the solderable surfaces of SMT parts...right?

I've sent some samples of QSE and QTE series connectors to a company
to
see if they can tin and remove the gold them for me. I hope they can,
but they may not be able to without a lot of bridging because of the
design of the connector. http://www.samtec.com/ftppub/pdf/QTE.PDF I
just
know I don't want to try and do it myself.

I think this connector was a bad choice as far as reliability is
concerned (but I'm not the customer). These connectors are being used
to
interconnect and stack with other boards, and there's no mechanical
support built into the connector other than the grounding strip that
runs down the middle of the connector. Plus we're putting down the
big,
tall -07 lead style connectors (they're almost 1-inch tall!)

So really look at the connectors carefully. There's a lot out there
and
they may seem like the perfect answer to eliminate a process
step...but
be careful!

-Steve Gregory-  

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting
Sent: Monday, May 07, 2007 11:05 AM
To: [log in to unmask] 
Subject: [TN] SMT connectors

Hi Techies,

What choices have you made regarding SMT connectors?

We are designing some new SMT boards and could put SMT connectors on
to
reduce or eliminate a wave or hand solder step.  I am looking at
D-subminiature connectors and 0.100 on center ribbon connectors.  Each
are available in SMT.  My concern is that the SMT is less durable in a
high usage or high vibration/shock environment.  Saving a step isn't
worth it if it created more long term failures.

Thanks in advance.

Phil

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