[SI-LIST] Re: PCB size Vs thickness
- From: msharpes@xxxxxxxxxx
- To: <sekraj@xxxxxxxxxxxxxx>
- Date: Wed, 28 Jan 2004 09:24:38 -0700
D. -- Thickness is usually determined by impedance design constraints
and number of layers - the height of the dielectric being part of that.
But, aside from that, other things come to mind like:
- through hole components and standard lead lengths,=20
- edge fingers, if any,
- aspect ratio of drilled holes (if you have small hole requirements,
like for a FBGA breakout)
- simple cost (more dielectric material =3D more cost)
Smallest finished hole sizes for .062in panels are in the 8mil
neighborhood, and increase for increasing thickness. I don't think
warpage and board thickness are related. As long as you have a balanced
construction with an even number of layers.
You mention an 18in X 12in board. I would recommend that you optimize
your board size if possible to a convenient panel size. The board shops
typically need a 0.75in to 1.0in border for resin flash, clamping and
racking. So, a 16in X 12in board size would be the maximum you could
fit on a 18in X 12in panel (which is a standard size in many resin
systems). Check with your board supplier and ask what the standard
panel sizes he uses for the resin system you've chosen. Some board
shops have a max panel size they can accommodate because of machine
requirements (i.e. their lam press, tank size, etc.).
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of D.Rajasekar
Sent: Wednesday, January 28, 2004 5:30 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] PCB size Vs thickness
HI all,
I need some guidence on deciding PCB thickness for 18" X 12"
board.
Since there is not much requirements on No.of routing layers & power
layers, i am more considerable to the mechanical aspects of the board
(like warpage,aspect ratio,etc.,).
can some point me the recommended pcb thickness for proposed pcb size
or vice versa? Where can i get those information?
Thanks,
-D.RAJASEKAR
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