Just a guessing: we happened to experience something likewise a year ago, even if our packages were much larger. When we put the packages on a polished granite table, we could clearly see that one 'wing' was up compared with the others. Accurate measurements gave that the coplanarity was locally >250microns. We thought that would be tolerated by the process, but it didn't. Some balls even showed dewetting. The supplier, a far eastern well known manufacturer, didn't argue about it, they simply took our return and sent new packages. As I said, just a thought, your description is somewhat vague.
Best wishes
Ingemar Hernefjord
Ericsson Microwave Systems

-----Original Message-----
From: Becerra Alejandro [mailto:[log in to unmask]]
Sent: den 6 augusti 2002 16:46
To: [log in to unmask]
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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