DDi is good but a little bit expensive.
You didn't say what is the ball diameter so we can compute the
reduction size of the footprint. If the ball  is 0.4mm diameter the
pad could be 0.35 to 0.4mm.
Which means you need no microvia, just a 8mil (0.2mm) through via with
18mil (0.45mm) outer ring.
Microvias is for 0.5mm pitch or lower.

Vasile

On 9/22/08, Zik Saleeba <zik@zikzak.net> wrote:
> TQFP is just too big for the project I'm working on so I'm looking at going
> to BGA for the first time. The process of breaking out those signals seems a
> little tricky. The package I'm looking at has 100 balls with 0.8mm spacing
> and I've been having some difficulty finding vias small enough to route the
> signals out using conventional board processes. The vias are just too large
> too allow enough clearance between the pads. A little reading around the web
> seems to indicate that at this density I should be looking at microvias
> rather than conventional vias.
>
> Have I got this right? Do I really need to go to a pcb fab which can do
> microvias? It seems like this counts out the cheaper-end fabs I'd normally
> use. Any suggestions on where I should go for fabrication? I'm only looking
> at prototypes and short runs and my budget is tight.
>
> Thanks,
> Zik
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