[PCB_FORUM] Re: Multi-layer stackup design
- From: "richard moffat" <richard.moffat@xxxxxxxxxxxxxxxxxxx>
- To: <icu-pcb-forum@xxxxxxxxxxxxx>
- Date: Thu, 23 Feb 2006 09:06:19 +1300
Re: BTW, is this Off-Topic? Are we allowed to discuss things like these here?
Even though this is a Cadence forum, I find it's often one of the best for
intelligent questions like this - unless someone can suggest a better one.
>>> josemagnaye4@xxxxxxxxx 22/02/2006 5:56 p.m. >>>
Yes, our standards specify at least 0.41mm if using a core material (laminate).
If less than or equal to 0.40mm then we need to specify 3 layer prepreg (sorry
for the wrong spelling before) but there were no minimum thickness specified.
After asking several vendors we also found out that there are no published
dielectric breakdown voltages for prepreg materials so we cannot compute for
the minimum. Of course we can always use the 2.0mm PCB thickness but without
proper justification ( i.e. literature or computed values), how can we convince
our sales dept and the customer to go with the higher PCB price?
BTW, is this Off-Topic? Are we allowed to discuss things like these here?
- JM
On 2/22/06, richard moffat <richard.moffat@xxxxxxxxxxxxxxxxxxx> wrote: 0.2mm?
Possibly (dare I say probably without any legal ramifications?)
The kind of spec it looks like you're referring to calls for 0.4mm. However,
that figure is negotiable. Creepage distance on the outer layers is more
troublesome.
You're certainly doing the right thing by layering more than one prepreg.
__________________________
Richard Moffat
PCB CAD Manager
Allied Telesis Labs
ph. +64 (3) 3393000
richard.moffat@xxxxxxxxxxxxxxxxxxx
>>> josemagnaye4@xxxxxxxxx 22/02/2006 3:51:48 p.m. >>>
Hi Claude
We're trying to design it to be as generic as possible since we will be using
several vendors. They can define which materials they can use for the prepeg
but the stackup design should be fixed.
Basically what we are trying to determine if 0.2mm thickness will be enough for
the 3 layer prepeg to withstand at least 1.5KV.
On 2/22/06, Claude Meyers <claude.meyers@xxxxxxxxxxxxxx > wrote:
This is a question you should be asking your fabrication house. Every PCB Fab
house has different requirements.
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Jose Magnaye
Sent: Tuesday, February 21, 2006 6:00 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Multi-layer stackup design
Hi!
We are designing an AC-DC power supply on a 4 layer board and we are currently
looking at any literature on how to design the stack-up.
Some of our primary and secondary tracks overlap and we were told that we can
let them overlap as long as we use 3 prepeg layers in between. Unfortunately,
we cannot find any info on the minimum allowed thickness of the 3 layers.
We are concerned with the thickness since we will be using a 1.6mm 4 layer FR4
board with 2 Oz copper on all layers.
JM
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