Mark
I have not seen a 104 pin in a long time. The number of rows will
determine how many layers you will need. Four rows two layers using top
side and one internal layer. It all depends on how far into the
BGA field your signal routes are. Typically you can route the first two
rows of a BGA on the top side with no vias after that you have to use an
inner layer and dog bone the BGA field. This will affect testing the
pins of the BGA that are routed on the top side only. If this is to be
Controlled Impeadance your stack -up will drive the trace width on the
outer layer and depending on the pitch of the BGA may not be routable
out of the second row of pins.

Paul


Mark Mainland wrote:

>
>
> Hello,
> Is it possible to break out on only 2 layers with a 104pin BGA? Its
> going on a 6 layer and the customer only wants traces on top and 1
> internal layer!
>
> Thanks,
> Mark
>
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