I don't recommend filling with anything. Vias that small, and shallow, allow
solder paste deposition and solderability, minus some possible outgassing.
Besides, plating 1 mil minimum copper thickness almost makes them plate
closed.

Earl Moon
----- Original Message -----
From: edward Edward Szpruch <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, September 14, 1999 5:01 AM
Subject: [TN] BGA micro-blind vias


> Hi,
> What is the common practice concerning blind-microvias located on BGA
pads:
> a) open ? ( 2-3 mills diameter, 2 mills deep)
> b) filled with what ( fill materials,LPI solder mask)?
> c) filled with electroplated copper ?
> Pls advice
>
> Edward Szpruch
> Eltek , Manager of Process Engineering
> P.O.Box 159 ; 49101 Petah Tikva Israel
> Tel  ++972 3 9395050 , Fax  ++972 3 9309581
> e-mail   [log in to unmask]
>
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