Hello Technetters, esp those deal with SMT, am just wondering
why my solder joint become powdery. I mounted SOIC-8 on a Nickel Au
finished
PCB using 63 Sn /35Pb/2Ag solder paste then subject it to PRCL reliability
test
the solder joint become powdery and i can removed the component
softly. Any explanation for this? I mean why it become powdery. I really
checked the
solder joint after reflow and It was good.

Same thing i did on BGA, i put bumped wafers on steam aged environment
and the solder balls after exposure become powdery.

Any theoretical or actual explanation on this

thanks

Jonathan Noquil
Package/Design (R&D)
Fairchild Semiconductor

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