Technetters:


We use an ASIC (20 mil) and occaisionally it seems we have some
solderability problems with it.  In looking at the pad size to a lead size,
the pad seems very large relative to the actual contact area of the lead.

Before I go to SM-782 and calculate what a pad size should be using the
MMC/LMC and all of the tolerances, I was wondering if there is a "rule of
thumb" for sizing pad/lead ratio as a quick check?

I was also wondering if the larger pad provides more solder for the
lead/pad wicking and filleting, or if the larger pad would allow the solder
to not become part of the pad/lead solder connection??

Assistance and opinions appreciated.

Tks.......DT

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