[SI-LIST] Re: copper thickness of a ref plane
- From: MikonCons@xxxxxxx
- To: si-list@xxxxxxxxxxxxx
- Date: Thu, 21 Jun 2001 13:11:46 EDT
Hi, Jim:
If properly implemented in a multilayer board, 1/2-ounce copper planes are
fine, particularly for high frequency designs. However, there are some
caveats.
Based on skin effect, the shielding (reduction in ground plane current from
one side to the other) offered by 1/2-ounce copper is ~26 dB (three skin
depths) at 120 MHz. Higher frequencies are better shielded, lower are not.
As an EMI consideration, low inductance is the main concern/target for
minimizing development of common mode noise; therefore, use efficient
paralleling of the reference planes by applying a reasonable grid pattern of
vias to interconnect the planes. This planning also has beneficial signal
integrity effects.
If you are delivering 30 or more amperes of Vcc current through the planes,
the total board power dissipation (and heat extraction) can become a problem.
Heavier copper planes help get the heat to the board edges and mounting
points.
In general, using 1/2-ounce copper aids etching accuracy, costs less, and
tends to tighten controlled impedance tolerances.
There are many more considerations, but that's my input for now.
Mike
Michael L. Conn
Owner/Principal Consultant
Mikon Consulting
(408)727-5697
*** Serving Your Needs with Technical Excellence ***
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List archives are viewable at: //www.freelists.org/archives/si-list
Old list archives are viewable at: http://www.qsl.net/wb6tpu
Other related posts:
