Mike,

Just to make obvious what others have already said.  The microvia will not
thieve an appreciable amount of solder if at all.  ALL soldered microvias, I
have cross sectioned so far, did have a tiny void in the solder joint that
filled the microvia.  Certainly not big enough to get up tight about.

Thanks

Ryan Grant
Advanced Technology Engineer
MCMS
(208) 898-1145
[log in to unmask]


> -----Original Message-----
> From: Michael Forrester [SMTP:[log in to unmask]]
> Sent: Thursday, March 08, 2001 2:25 PM
> To:   [log in to unmask]
> Subject:      [TN] MicroVia In Pad Vs Silver VIA fill
>
> We currently have a design with  15 X 15 array BGA patterns a 12 layer
> 0.62 bd.
> There are 10 mil vias in every BGA pad (22 mil pad) .
> The reason for the Via in pad is keep the runs as short as possible.
> Currently
> we fill the vias with conductive silver epoxy and plate E Ni/I Au
> over the entire pad surface.  I would like to try a microvia in pad, no
> via
> fill, and OSP.  My questions are:
>
>           1) Can I get away with not filling the microvia to prevent
> solder
> thieving?
>           2) Are there any problems with this approach?  If NG, other
> ideas to
> get rid of silver fill?
>           3) Is there any disadvantage/reliability risk, to using silver
> via
> fill other than cost and longer lead time?
>
>      Thank you in advance.
>
> Best Regards,
>
> Michael Forrester
>
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