[SI-LIST] Re: PCB Stackup - 4 vs 6 layers
- From: "Richard Feldman" <rfeldman@xxxxxxxxxxx>
- To: <kevin98146@xxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Tue, 21 Sep 2004 15:59:14 -0700
Kevin: your question looks as if you are misusing the term "core".
Core doesn't imply the center of a multilayer stack-up,=20
or the one with the thickest dielectric.
The copper-clad parts etched before lamination are cores.
Other dielectric layers include bonding material, which
comes without copper, and goes in just before lamination.
You can specify the thickness of all your dielectric layers.
But in most applications, you don't care which are cores.
Then leave that decision to the fab vendor.
It can't increase the cost, and may reduce it.
For example, your 6-layer stackup has three cores to process=20
before lamination. It might be less costly with two cores,
as shown below, especially if your signal and GND/PWR layers
have the same thickness of copper.
Sig
dielectric
GND
core dielectric
Sig
dielectric
Sig
core dielectric
PWR
dielectric
Sig
That still is more cores than your 4-layer stackup.
You didn't mention a 6-layer order with GND and PWR=20
closest to the center, but that's a different topic.
Respectfully submitted,
Rich Feldman
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Kevin Khuu
> Sent: Tuesday, September 21, 2004 2:29 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] PCB Stackup - 4 vs 6 layers
>=20
>=20
> Given both PCBs have the same dimensions (Width and length)=20
> and thickness,=20
> which stackup is cheaper to build?
>=20
> 4-layer PCB with a big core
>=20
> Sig
> GND
> Big Core
> PWR
> Sig
>=20
>=20
> or 6-layer PCB with a smaller core
>=20
> Sig
> GND
> Sig
> Smaller Core
> Sig
> PWR
> Sig
>=20
>=20
> Thanks,
> Kevin
>=20
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