Ken

As far as I'm aware, you can do this easily with blind microvias but it
is extremely hairy with conventional drilled vias, even blind. Just do a
quick calculation of the amount of solder in the deposited paste and the
amount that should be needed to fill the via with the menisci. Ergo,
quod est demonstrandum, none left for the solder joint :-(

Brian

Ken Patel wrote:
>
> Guys,
> On our nickel gold board, solder joints are below IPC spec (insufficient
> solder) where there are vias in pad. Solder is drained down the via
> holes and deprived the joint of necessary solder.  I would like to know
> the following.
> (1) How about using the surface finish 63/37 coating HASL instead of
> Ni-Gold? I think gold dissolves in solder so quickly that I rather use
> HASL processed boards, any thoughts?
> (2) Do you guys mask the via on bottom side to avoid solder draining out
> on the other side?
> (3) Does anybody try Hi Temp solder paste to fill the vias as our
> assembly house ordered via stencils to fill the via using eutectic
> (63/37) solder paste which didn't work?
>
> Looking for
> re,
> Ken Patel
>
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