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October 2007

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Subject:
From:
Ahne Oosterhof <[log in to unmask]>
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Date:
Tue, 30 Oct 2007 18:54:31 -0700
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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: [log in to unmask]
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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