Zik Saleeba 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
>   
If the chip is also availible in 1mm spacing you might want to consider 
going for that. .2mm may not sound like much but on a process with .1mm 
track and gap it is one extra track between each pair of vias.

Does the BGA have a cluster of power and ground in the middle? (If so it 
makes life a lot easier)
> 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. 
How large are your vias? The board I did recently with a 1mm spacing BGA 
used .3mm via holes and .5mm via pads and .1mm tracks. That allowed me 
to get two tracks out on each layer between a pair of vias and afaict 
such vias are still large enough to be drilled in the conventional 
manner. I still needed 8 layers but the BGA was quite a lot bigger than 
yours and space was tight.

If you can get a 1mm spacing version of the BGA and your chip has 
power/ground in the middle then you could probably achive what you need 
on something like PCB trains 6 layer process.

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