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October 2007

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Subject:
From:
"Gumpert, Ben" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Gumpert, Ben
Date:
Wed, 31 Oct 2007 06:11:23 -0400
Content-Type:
text/plain
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text/plain (130 lines)
I have some similar connectors, and the problem appears to be from the
construction of the connector. Looking at the bottom of the connector,
the inner row connections are installed to one side of the individual
bottom openings, and the outer row connections are installed to the
other side of their openings. Since the tails alternate between inner
and outer, you end up with the every-other-pin misalignment shown in the
images when the inner row tails and the outer row tails aren't installed
well relative to each other.

Ben

-----Original Message-----
From: Ahne Oosterhof [mailto:[log in to unmask]] 
Sent: Tuesday, October 30, 2007 9:55 PM
Subject: Re: Samtec SMT Connector Woe's...(again)

It looks like there could be a lot a play in the connector terminal
(connector design issue). If so, the only way to make more sure of
having the terminal on the pad is to make the pads wider (board design
issue).
There seems to be room to do so. If there is no play in the terminal,
wider pads still would solve your problem. 
It also looks like only the very end of the terminal is >25% off the
pad. I cannot see how much it is off farther in. Maybe it is less than
25% off if you go by area. :) 

The reason for the problem could be the design of the connector or
"damage"
of the bent terminal kind (packaging issue??).

Good luck,
Ahne.

 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, 30 October, 2007 12:52
To: 
Subject: [TN] Samtec SMT Connector Woe's...(again)

Hi All,
 
I'm running into a problem with some Samtec connectors again, and maybe
you all can guide me on how I should handle this...
 
First here's a picture of the connector:
 
http://stevezeva.homestead.com/files/Samtec_Connector.jpg
 
Next, here's a picture of the problem:
 
http://stevezeva.homestead.com/files/Samtec_Solder_Joints.jpg
 
QA is calling these solder joints as rejectable. These leads aren't
gull-wing leads. I view them as some sort of mutated butt joint leads
(sort of). I don't know what you would call them really, so I'm not
quite sure what inspection criteria you would use. As you can see, the
toe of every other lead doesn't sit 100% over the pad, and it continues
like that through-out the length of the connector. I see that as a
connector manufacturing issue, not something we have any control over.
 
Here's a picture of the bottomside of the connector so that you can see
what the bottom construction of the connector looks like:
 
http://stevezeva.homestead.com/files/Samtec_Bottom.jpg
 
In the top of the picture you see what Samtec calls a locking tab, one
at each end of the connector. It has barbs that dig into the PCB and you
have to force them into the holes. Obviously, we're hand placing them.
What's funny is that they come in tape and reel and the have a pick and
place pad on them! I don't know of any pick and place machine that has
enough force to place these connectors and push the locking tabs into
the holes so that the leads sit flush on the pads. I've also posted
Samtec's drawing of the connector:  
 
http://stevezeva.homestead.com/files/SAMTEC_ROLC.pdf
 
My gut feel is that the solder joints are acceptable. If the toe of
these leads are tweeked a little, there's still a good percentage of the
lead over top of the pads in which to form a decent solder joint because
of the way the connector and leads are constructed.
 
What say you all?
 
Thanks!
 
Steve Gregory
 
P.S. I HATE Samtec connectors!!!!!
 
 

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