Hi! Werner and  I haven't responded because we were both at the same
technical conference working  Pbfree  soldering issues! I have been witness
to several cases where we thermal cycled solder joints which had been
"disturbed" during the reflow cooling cycle. The solder joint reliability
was several hundred thermal cycles lower than non-disturbed solder joints
(as measured using Class 3 type reliability figures of merit). The solder
microstructure was not the leading issue although I felt it was a
contributing cause of degradation. The main root cause issue appeared to be
the nonuniformity/non-symetricalness of the solder joint shape which was
the location of several solder joint cracks which ultimately became opens.

Dave Hillman
Rockwell Collins
[log in to unmask]




                      Guy Ramsey
                      <[log in to unmask]        To:       [log in to unmask]
                      RG>                      cc:
                      Sent by: TechNet         Subject:  Re: [TN]
                      <[log in to unmask]>


                      02/11/2003 04:26
                      PM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to Guy
                      Ramsey






I'm sure that Dave Hillman or Werner are more qualified but I noticed no
answers to your post. I'll take a stab at it and perhaps stir the pot.
A disturbed connection was moved during the transition from liquid to
solid. Movement during this time changes the grain structure of the
connection in unpredictable and undesirable ways. Cracking may begin
earlier in the life of the connection compared to an undisturbed solder
joint.

> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of farnam_jack
> Sent: Tuesday, February 11, 2003 2:30 PM
> To: [log in to unmask]
> Subject: [TN]
>
>
> How is solder joint reliability effected over time in the
> case of disturbed solder (12.4.6)?
>
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