Hi Ted,

Padsizes you can find in IPC-SM-782 or IPC's online footprint
calculator. 12 mil width is standard, anything smaller than that may
result in problems with paste printing. This leaves hardly any space for
a good solder mask stripe, therefore it is quite common to have one
large soldermask window around each row of pads, although some would
argue that you need soldermask between each individual pad to get good
gasketing of the stencil while printing solder paste. You may need the
inner layers for the fan-out pattern, but that doesn't mean you need
via-in-pad. When possible use ordinary via's for this.
Hope this helps.

Daan Terstegge
Thales Communications
Unclassified mail
Personal Website: http://www.smtinfo.net

>>> [log in to unmask] 12/14/03 02:59am >>>
Hi all,

Want to find out what pad size and solder mask opening
are people using for .5 mm pitch components?  Since
the pad size is so small, it is a must to use solder
mask define pads?  Are people using via-in-pads to get
traces out or just using the outer layers?  Thanks all
in advance.

Ted Kong.

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