Alejandro, I think we need a better deescription of your "non-soldering"
phenomenon, and how did you check your thermal profile? It's unlikely that
lack of coplanarity affects solderability, unless leads are so bent that
they don't sit in the solder. Your component data sheet should state the
coplanarity tolerances for the part in question.

Does the problem occur in the  same place(s) each time? You could try
turning the board around and reflowing it with a different leading edge and
see if there's a difference. Non-soldering to me, though, means you have a
serious oxidation or contamination problem.

Otherwise:
What is your board finish (HASL, ENIG, Tin, Silver ...?
How old are the boards?
What is the component lead finish?
How old are the components?
What are your storage conditions like?

We need more gen. Any pictures you can post on Steve's site for us to look
at?

Peter



Becerra Alejandro <[log in to unmask]>      06/08/2002 10:46 PM
Sent by: TechNet <[log in to unmask]>

Please respond to "TechNet E-Mail Forum."; Please respond to Becerra
Alejandro

              To:  [log in to unmask]
              cc:  (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
              Subject: [TN] Coplanarity in QFP208








Hello to All,


We are having Non Soldering problems in a QFP208 (Pitch is 0.5 mm or 20
mils)
The problem is focused in one area of the component.
We already checked the reflow profile and Solder paste printing and both
are OK.
We realized that the components have coplanarity in the area with failures.

What is the maximum coplanarity accepted for this type of components?


Thanks,


Alejandro Becerra


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