Hi Poh,
You do not say anything about the QFP leads. You most likely had no wetting to
the leads. Observe the solder joints remaining on the PCB pads; if you can see
a clear outline of the lead foot in the the solder, you have a clear
indication of inadequate wetting. This could then be a reflow process issue
(inadequate reflow heat), a solderability issue (leads are not solderable
because of contamination/oxidation —remember, plated but not reflowed tin/lead
does not protect the underlying surface very well nor has the surface had to
be solderable at the time of tin/lead plating), or an improper lead material
(some lead materials, e.g., Alloy 42, BeCu, have been known to be difficult or
impossible to solder).
Please let us know what you find.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask]


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