Hi Ioan,
Earlier this week I visited IPC's lead-free conference in Brussels, and
what I understood from several presentations is that the stencil process
isn't changing very much, although several speakers suggested to have
slightly larger openings to compensate for the worse wettability of the
new materials. Especially on OSP coatings the solder wets only where it
is applied, without further spreading over the pad.
Another issue is that tombstoning will become a bigger problem due to
higher surface tension (especially in nitrogen atmosphere), which could
possibly be another reason for adjusting stencil apertures.
Daan Terstegge
Thales Communications
Unclassified mail
Personal Website: http://www.smtinfo.net
>>> [log in to unmask] 06/12/03 01:40am >>>
Hi Technos,
since there are not so many takers for Sasha's problems, I wonder if I
could
tease you some more.
OK, there will be issues with material control, duplicate BOMs and
AVLs,
removable solder pots, etc. But, what about the stencils? Will I be
able to
use the stencils I use right now, or they are too contaminated with Pb?
Is
the rheology of the PB-free paste identical to the one of the SnPb?
Should I
keep the homeplating, or the full apertures will be OK?
Thanks,
Ioan
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