[SI-LIST] Re: 1 oz vs. 1/2 oz cu

Greg,

As always it's best to check with your PCB vendor to see what their
capbilities are. In general they don't seem to like narrow air gaps (e.g.
<0.005") especially in combination with narrow traces in 1oz copper, due to
the way the etch process works. That doesn't mean impossible - they can make
almost any board once - just that cost may be high due to low yield.

A slight advantage of using 1oz copper for all layers is that the cores
required will have the same copper weight both sides of the laminate, which
I understand can be a bit cheaper and easier to obtain in mass-production.
Having said that, I did once do a board that needed a core 1/2oz one side
and 2oz the other.

1oz traces of course have lower dc resistance which is always welcome, but
offer a smaller advantage over 1/2oz at frequencies where skin effect is in
play.

peter arnold


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Inchauspe, Greg E
Sent: Tuesday, April 27, 2004 9:39 AM
To: Sig Integ Group
Subject: [SI-LIST] 1 oz vs. 1/2 oz cu


Hello SI,

I'm working on a 18 layer board stack-up and was wondering what the =
trade-offs are between going with 1 oz Cu signal layers and =BD oz Cu =
signal layers.  All power and ground are 1 oz Cu.

Thanks,
Greg
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