When it's not only shadowing, it might be a combination of a little bit
of shadowing with a non-optimal solderability ? Or perhaps the soldering
pads are contaminated with glue ? (i.e. a hardly visible film, due to
improper cleaning of a bad-glued board). Good luck !

KARLA DUGGAN wrote:
>
> We are currently having problems soldering SOT23 parts on
> the bottom side of a board.  We glue the bottom side surface
> mount components and then run through the reflow oven to
> cure the glue.  We then run the boards through the wave
> using both a chip and lambda wave.
>
> All the SMT components solder except the SOT23.  The
> SOT23 is randomly soldered.  Sometimes 2 leads,
> sometimes 1 lead, sometimes all leads, sometimes no
> leads.  The shadowing can be accounted for but not all the
> missing solder is due to shadowing.
>
> Has anyone experienced such problems.
>
> Any help is greatly appreciated,
> Karla Duggan
> APACTS

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