Ioan,
Butt joints are feared not good due to the near non existent interface area; component terminal area to PCB pad area requiring all joint strength to be gathered at "heel" and not having a wide pad width heels are minimum in length. The the big "problem" in the butt joint is snipping of lead prior to soldering would leave the device terminal uncoated and nasty pin material hidden in the heeled joint.  This is from the old days of through hole and the "terminal" was usually an IC lead and mostly side brazed (non brazed can be easily formed to be plannar mounted).  The other paradigm of "No Buts" is from wire soldering where Butt joints are not acceptable workmanship configurations even today.
In SMT configurations non wetting will still occur at the end of trimmed leads, which in itself is may or may not be a problem.  The Butt joint concern in an SMT application would be from lead non forgivingness -aka compliance- such as our old friend the TSOP; short stiff leads.  The reliability of this depends on application, ask yourself if this is running your oxygen bottle, do you feel good.  
In Military applications all it takes is one person yelling "Butt Joint!" to ruin your whole day. Thought I'd share a little butt experience.  
Good luck with it,
Brad
  ----- Original Message ----- 
  From: Tempea, Ioan<mailto:[log in to unmask]> 
  To: [log in to unmask]<mailto:[log in to unmask]> 
  Sent: Tuesday, September 05, 2006 4:30 PM
  Subject: [TN] Connector reliability


  Hi Technos,

  I would like what you think about the reliability of the joints formed by this connector http://samtec.com/ftppub/pdf/SFMH_SM.PDF<http://samtec.com/ftppub/pdf/SFMH_SM.PDF>

  It looks pretty much like a butt joint to me, no real compliance.

  And since we're here, what about SMT headers, with their massive pins, are they reliable?

  Thanks,

  Ioan

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