Jonathan we cannot see your picture so we cannot really advise you. Can you
send this question again with the picture? Is this part connected to a power
or ground plane of any significance? What kind of chip is it?

Dorothy Lush

> ----------
> From:         Jonathan A Noquil[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;[log in to unmask]
> Sent:         Wednesday, July 25, 2001 5:07 AM
> To:   [log in to unmask]
> Subject:      Non-Reflow
> 
> Hello Friends,
> Can anybody explain why there is always a non-reflow
> of solder paste as shown by the drawing below?
> 
> 
> (Embedded image moved to file: pic07711.pcx)
> 
> The solder paste used for assembly was
> 88Pb10Sn2Ag and it is an Indium No clean paste.
> Its liquidus temp was 290 C and solidus temp of 268 C.
> 
> Reflow Atmosphere: N2 purge as hot gas and cool gas (shown at the above
> drawing)
> although we tried to increase the temp to over than 300 C, it is still the
> same results.
> I tried the paste to other oven with a forming gas blanket, and reflow it
> to a peak of 295 C
> the results were good (All reflowed).
> 
> We had profiled the above oven at 3 points Left edge, Midle and. Right
> edge
> and
> temperature difference vs setting was ± 5 degree C on that three points.
> 
> Was the non-reflow due to the blanket? O2 ppm level? But why on the left
> side only?
> Does a localized heating have occured? But the temp profile was okay?
> 
> Do you have any insights that you can share?
> 
> God Bless You All...
> Thanks
> 
> 
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