Mr. Baggett,

        some answers for your questions 3 and 4.
        My experience is either to tent the vias only half or tenting them with
selkscreen (if this is the right word for the lacquer used to show the
component-positions).
1) The first Idea means to use a soldermask covering the pad but leaving the
holes open. Because my manufacturer told me not to use completely tented vias
with HAL-soldering (I am still using HotAirLeveling-process) for the air in the
via burst open the soldermask. Protel allows a negative soldermask expansion for
vias (and 99SE allows it layer-specific if you need it)
2) The second Idea is a makeshift. For these process can be done after HAL but
havenīt got the precision, you have to place silkscreenpoints manualy and you
perhaps have problems if a plane surface is needed. On the other hand you can
use the points only where you need it. And you have less problems in
komunikation with your board house.

        Hope it helps a little.

        Waldemar


Bagotronix Tech Support schrieb:
> 
> Hello, all:
> 
> I am designing a board with a 388 BGA chip.  I have questions about vias:
> 
> 1)  Should I tent the vias under the BGA?
> 2)  If (1) is yes, should I tent other vias on the board?
> 3)  If (1) is yes, what substance/method is used to tent vias?
> 4)  If (1) is yes, what do I tell the PCB fab house to get them to tent the
> vias?  Is it as simple as "tent the vias"?
> 5)  If blind vias are used, do they need tenting also?
> 
> The BGA has a 1.27mm ball grid.  I am considering a 25 mil pad, 12 mil via,
> 31 mil solder mask opening diameter.  Does this sound good?  If not, what
> would you recommend?
> 
 - - snip - -

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