LISTSERV - TECHNET Archives - LISTSERV.IPC.ORG

TECHNET Archives

September 1997

TechNet@IPC.ORG

	LISTSERV Archives
	TECHNET Home
	TECHNET September 1997

	Log In
	Register

	Subscribe or Unsubscribe

	Search Archives

Options:	Use Monospaced Font Show Text Part by Default Show All Mail Headers
Message:	[<< First] [< Prev] [Next >] [Last >>]
Topic:	[<< First] [< Prev] [Next >] [Last >>]
Author:	[<< First] [< Prev] [Next >] [Last >>]

Subject:	Re: MLB Layer Construction and Plane layer selection
From:	Jack Olson <[log in to unmask]>
Reply To:	TechNet Mail Forum.
Date:	Fri, 19 Sep 1997 09:03:21 -0700
Content-Type:	text/plain
Parts/Attachments:	text/plain (47 lines)

From:    "Varadaraj.K" <[log in to unmask]>
> What is the correct procedure to choose Plane layers in a given MLB?.
> Is it dependent on Layer construction of a given Fabricator? OR
> Is it dependent on Impedanc MAtching? OR
> Is it the Capacitive decoupling effect between the power/gnd planes? OR
> are there some more considerations to this choice?.

I am no expert, but there are plenty who will correct me if I am wrong,
so I will try to answer:

Only a percentage of designs are impedance controlled, and in these
cases the drawing should show whether the controlled signals are on top
of a ground plane or between two planes or whatever.
If you are a fabricator asking these questions; If it is not clear on
the drawing CALL THEM and resolve it before you go any furthur!
If you are a designer/engineer asking these questions: You better have
this figured out BEFORE it ever gets to the fabricator!

If there is only one plane, you almost can't avoid an unbalanced
construction, unless other layers have poured copper, so it probably
doesn't matter (but this is uncommon anyway)

If there are two planes, they should be located next to each other for
better coupling, and be "centered" in the stackup to avoid warping.

If there are many planes, they can probably be "paired up" (a designer
or engineer should be aware of this anyway, pairing +5 with GND, and
+15/+12 with AGND or whatever) and placed "equidistant?" from the
center.

Hope that helps a little...                                     Jack

(Also, ask around, several books are available that could provide some
illustrations, too)

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
##############################################################

ATOM RSS1 RSS2

LISTSERV.IPC.ORG