Re: PCB drawing


icegray wrote:
> You think autoroter is useful when using CSP, BGA products?

I've never used an autorouter that can handle the dense routing that
BGA's create. I've even given hand routed netlists to others to
autoroute
only to have the autorouter create a mess of the space with vias and
generally not even be able to route the existing design (Cadence router
last year on a PC104+ design with BG560, several large QFP/TSOP
packages and misc parts. that was already hand routed with PCB).

Routing BGA's, especially those with more than 500 pads, is very
difficult
to do manhattan, and generally requires establishing "flows" of traces
in
both dimensions to connect to cpus, memory and connectors which have
high
pinouts. This requires a lot of placement thought.

The big advantage of hand routing BGAs is choosing pins/pads to route
easy, not picking pins/pads arbitrarily and hoping the pins swap
function
(if any) can get it right.

.

Relevant Pages

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